Called the “Age of the Scientific Revolution,” the seventeenth century represents a major turning point in the history of science. Instead of asking why things occur, scientists turned to how things happen—a shift in emphasis from speculation to experimentation. Interpretations became mechanistic, and the language of science became mathematical.
Influences from the Past
Three major influences from earlier centuries had to be reckoned with: Aristotelianism, Galenism, and Paracelsianism.
Aristotelianism in the seventeenth century was really a general view of nature, especially with respect to the physical sciences and biology. In the two thousand years following his death, Aristotle’s original doctrines had gone through numerous changes by various cultures. Prior to the seventeenth century, the experimental method springing from Aristotle frequently consisted of no more than a single observation, often of a chance nature, and for the most part not quantified nor expressed in mathematical terms.
An influence on the seventeenth century reinforced by Aristotelianism was the intimate relationship between astrology and medicine. Aristotle’s conception of a spherical earth in a spherical universe of finite size, moving according to mechanical plan, fitted well into the subsequent concepts of astrology. Chance was usually not a factor in the Aristotelian universe. However, the purpose of an occurrence was not necessarily obvious but rather an element of a plan that could be figured out. In astronomy there was a regularity and uniformity that was especially evident. This teleology, as seen in Galen’s teachings, continued to be an important part of medicine until the seventeenth century, when Aristotelianism came under heavy attack.
Another influence on seventeenth-century medicine was Galenism, which, like Aristotelianism, embraced more than the concepts developed by Galen in the second century A.D. His works demonstrated a search for facts (although colored by preconceptions), a vigorous disrespect for authority (although he did worship Hippocrates), and a strong desire to see for himself. However, his numerous disciples tended to accept what Galen said he saw rather than follow his methods.
An additional important factor was Paracelsian thought inherited from the Renaissance. In opposing the long-term medieval reliance on the works of Galen and Avicenna, and in emphasizing observation and experience, Paracelsus was a revolutionary. He revived Hippocrates as the only physician of the past worth remembering, yet his own system was itself “un-Hippocratic.” To him the physician was a magus who could direct the astral forces to heal. As the constellations changed so must diseases and their treatment; thus astrology became an important aspect of Paracelsian doctrine.
The most notable influence of Paracelsus was on chemistry in medicine. He concluded that the human body was a chemical machine, and whereas Galenic physicians had relied primarily on plant medicines Paracelsus popularized the use of minerals. This chemical medicine was to compete with the Galenic school for the next two hundred years and ultimately to find a place in the accepted pharmacopoeias.
Philosophies of the Century
Rene Descartes (1596-1650) represented ideas that were in some ways a transition between earlier systems of philosophy and the directions thought would take after the seventeenth century. Descartes’s Discourse on Method in 1637 supported a generalization of the mathematical method and the development of a mechanistic picture of the world. Descartes began with general ideas arrived at intuitively from self-evident truths and from them deduced the phenomena of the world. To Descartes experiment was chiefly illustrative, but useful when deductive reasoning was inconclusive. Thus Descartes perpetuated the scholasticism and speculative tendencies of past tradition. On the other hand, he was generally opposed to an Aristotelian teleology, for to Descartes all natural objects were machines ruled by mechanistic principles.
Another philosopher of science was Francis Bacon (1561-1626). Apparently the inductive method he proposed did not have a marked effect on contemporary scientists, nor did he side with Copernicus (1473-1543), the advocate of a heliocentric world. Furthermore, some of his works were not well known until after his death. He was, nevertheless, an eloquent spokesman for experimentation and the inductive method, which was to collect particular facts with no hypothesis in mind and look for a general theory to emerge.
Bacon, like Descartes, viewed science as utilitarian. He saw humankind as ever moving ahead and accumulating the benefits of scientific endeavor, but the idea of Progress was something new to the seventeenth century. The Greeks had considered science primarily speculative and philosophical rather than the means of exerting power over nature. To most ancient people, time and the world were cyclical rather than progressive: civilizations rose and fell. Men generally felt that the present was in decline from a past Golden Age. Like Bacon, Descartes also subscribed to the idea of progress, but he believed that his own speculative thoughts could point the way ahead. Bacon on the other hand considered his method of reasoning from facts as merely a first attempt upon which others would improve.
New Directions of Medical Thought
Iatrochemistry, or medical chemistry, was the name given to the fusion of alchemy, medicine, and chemistry that was practiced by the followers of Paracelsus in the sixteenth and seventeenth centuries—an alternative to the new mechanistic philosophy which eventually dominated modern science.
Jan Baptista van Helmont (1577-1644) was the leading Paracelsian and iatrochemist of the seventeenth century. After taking a medical degree in 1599, Van Helmont became increasingly dissatisfied with the bookish Galenic medicine practiced in the schools and eventually took up a career of private research. His opposition to the established doctrines of medicine and to medical teachings of churchmen brought him into conflict with the Spanish Inquisition, which badgered him throughout much of his life.
Van Helmont advocated quantification and experiment, and his comparison of the weight of urine with that of water was the first measurement of its specific gravity. Another contribution was his recognition that air was composed of several gases. He actually coined the term “gas” (derived from the Greek and Latin “chaos”).
Van Helmont believed that the basic substances of the world were not the four elements of Aristotle and Galen nor the three principles of Paracelsus. Instead he thought of all matter as reducible to water, which he said was supported by Scripture: on the second day God created the firmament to separate the waters above from the waters below, but nowhere in the Bible did it say that God created the water.
Like Paracelsus, Van Helmont was a founder of the concept of disease as a distinct entity existing parasitically in the body. This was in contradistinction to the Galenic concept that disease was part of the person and represented a derangement of the humors. Unlike Paracelsus, Van Helmont did not accept astrological principles as affecting disease, nor did he consider valid the Paracelsian analogy between microcosm and macrocosm.
By experiment he concluded that ferments (enzymes) were a fundamental part of all physiological mechanisms, which is not far from our contemporary views. Van Helmont’s rejection of the Galenic conception of disease also caused him to reject the therapeutics. Fever was not putrefaction of the humors but represented reaction to an invading, irritating agent. He declined to use bloodletting and purging, and rejected their supposed value in restoring the humoral balance. He used chemical medicines and improved on the use of mercury, which Paracelsus had so vigorously advocated.
Another important iatrochemist was Franz de le Boa, called Franciscus Sylvius (1614-72). His approach to medicine was empirical, making use of the newest discoveries in chemistry. His theory did not include the humors of Galen but was based on the concept of bodily acids, bases, and their neutralizations. In relying on direct observation and experience he was representative of the iatrochemists of the second half of the seventeenth century. Although his experiments, from which he made sweeping generalizations, were really little more than observations, he provided a foundation for a new system of medicine based on iatrochemical concepts. Furthermore, he made the laboratory an essential tool for the practice and teaching of medicine.
Sylvius’s attitudes also helped to bring bedside teaching into its own again. For centuries there had been no systematic clinical teaching, for the universities awarded medical degrees on the basis of spoken disputations. Leiden, where Sylvius worked, was one of the first cities to institute clinical teaching (1636), and since Holland was a center of religious toleration students flocked into Leiden for instruction and study.
The rise of atomism was of utmost importance to the development of science, and consequently of medicine. The concept had its origins in antiquity and was first fully developed by Democritus of Abdera and Leucippus of Miletus (c. fifth century B.C.). The differences in physical objects were due to the shape, arrangement, and motion of atoms, which were infinite in number and dispersed throughout an infinite void. Atomism had been revived in the third century B.C. by Epicurus, whose primary interests were in ethics rather than in natural science. However, the survival of atomism was due in no small part to the Roman poet Titus Lucretius Carus of the first century B.C., who put the doctrines of Epicurus in the form of an elegant poem, De rerum natura. Not popular in the Middle Ages because of its atheistic tone, the work was rediscovered during the Renaissance and given further currency in the seventeenth century through the efforts of Pierre Gassend (1592-1655).
Gassend was a Catholic priest with a wide scientific reputation and orthodox religious beliefs. To make atomism fully acceptable in religious thought he had to divest matter of its eternal nature. Since God had created the atoms, he should be able to destroy them. Moreover, their motions were not determined by chance or necessity but by God’s constant intervention.
Robert Boyle (1627-91) was another important proponent of atomism. However, unlike most seventeenth-century physicists, he was not principally interested in mathematics. Boyle devised the air pump with which he demonstrated the necessity of air for life. He also formulated what has come to be called “Boyle’s Law”: the volume of a gas varies inversely with the pressure at a constant temperature. His writings covered a variety of subjects, including respiration, magnetism, blood chemistry, and even wine.
Although not a physician, Boyle did extensive work with medicinals, which brought him into contact with patients. Boyle’s empiric use of “specifick medicine” was a more scientific approach than the employment of drugs according to their Galenic classification. The recognition that something worked, even if there was no explanation, was a step forward. On the other hand, his choice of medication sometimes betrayed his allegiance to an ancient idea of “like cures like” still prevalent in the seventeenth century: for instance, that jasper was of value in preventing hemorrhagic disease because of its red color. This principle of “sympathy,” which was important to Paracelsus, was to continue into the nineteenth century and to find endorsement by Samuel Hahnemann (1755-1843) with his homeopathy.
Another champion of modern science was Galileo Galilei (1564-1642). Some scholars believe that Galileo worked from experimental observations while others conclude that he worked from purely theoretical considerations, using experimentation to dress up his conclusions after the fact. Nevertheless his contributions were gigantic. Galileo formulated the laws of motion in a mathematical manner as they apply on the earth. It was the genius of Sir Isaac Newton (1642-1727) to extend these laws to the heavens by accurately describing the movements of the objects in our solar system under the influence of universal gravitation.
The explanation in medicine of phenomena as objects in motion resembling machines was iatromechanics, or iatrophysics. Giovanni Alfonso Borelli (1608-79) was the leading iatromechanist of the seventeenth century. Influenced by Galileo, he sought to apply his mechanical principles to medicine. Starting with a simple unit, the muscle, and then expanding his investigation to more complex systems in the body, he finally studied the whole organism.
Giorgio Baglivi (1669-1707) represented the extreme use of iatromechanics, likening each organ to a specific machine. Another iatromechanic was Santorio Santorio (1561-1636), who constructed thermometers and is best remembered for his research into the physiology of metabolism. By means of a balance mechanism he measured the weight changes that result from eating, excreting, and perspiring.
In 1677 Antony van Leeuwenhoek (1632-1723), a linen merchant of Delft, discovered the male spermatozoa with the aid of a microscope. Another Dutchman, Niklaas Hartsoeker (1656-1725), soon after Leeuwenhoek, published pictures showing tiny preformed men (“homunculi”) in the spermatozoa he examined through a microscope. By the end of the seventeenth century there were two opposing views on how the embryo originated. Preformation, the dominant theory, saw a minuscule individual present in the sperm or egg, for which embryonic development was merely adding matter until the growing fetus reached newborn size. The other theory, epigenesis, taught that the organism began as a primitive substance that changed through a series of stages, gradually developing different structures and expanding others until the nature of the mature embryo was attained. In the seventeenth century preformation better fit the mechanistic attitude of science—the occurrence and maturation of the new organism was thereby explicable in secular, rational, and material terms. Epigenesis, on the other hand, seemed to require a spiritual, vitalistic theory to account for the seemingly occult change from formless matter into an organized creature.
William Harvey subscribed to the epigenetic explanation, and although some of his reports contained factual errors he made important contributions to embryology. It was his pioneer work on the circulation of the blood, however, which has gained him a prime position in the history of medicine.
CIRCULATION OF THE BLOOD
The brilliant proof by William Harvey (1578-1657) of the continuous circulation of the blood within a contained system was the seventeenth century’s most significant achievement in physiology and medicine.
Of course Harvey had had precursors. In Galenic physiology, blood was thought to be produced in the liver, where it received “natural spirit” and from which it flowed out to the periphery of the body due to a pulling or attractive force. Furthermore, blood obtained “vital spirits” in the heart and “animal spirits” in the brain. When Galen looked at the living heart in the second century A.D., he saw that it did not contract in a simple manner. First one side contracted and then the other, which did not seem to him the action of a pump. This movement was to Galen evidence of a displacement of blood from the right chamber of the heart into the left through tiny pores in the separating membrane.
The first person in the European tradition to propose a separate transit of the blood through the lungs was Michael Servetus (1511-53). Matteo Realdo Colombo (1516?-59) put forward a similar theory of the pulmonary transit solely on the basis of physiological reasoning. Since, contrary to Galen, the septum of the heart was solid, blood must follow another path from the right chamber to the left. The pulmonary artery coming from the right chamber seemed too large for the simple purpose of nourishing the lungs with blood, but blood in the pulmonary vein going into the heart’s left chamber from the lungs was bright red whereas blood traveling to the lungs was dark red. He reasoned that it was the same liquid, but the change in color must be due to some action in the lungs.
Andrea Cesalpino (1519-1603) was perhaps the most important of Harvey’s precursors. Not only did he use the expression “circulation” and think in terms of a closed circulatory system, but he had some straightforward ideas about the greater and lesser circulation (pulmonary transit). His astuteness was also shown in his proposal that fine vessels, or capillaries, connected the arterial and venous systems, so that there was no free, open effusion of blood into the tissues—as had been assumed for many centuries. On the other hand, Cesalpino believed that in addition to the capillaries there were major direct connections between the larger arteries and veins. Furthermore, Cesalpino believed that blood originated in the heart. He thought of circulation in terms of hot blood rising in the arteries and cold blood falling in the veins, but he had no clear conception of the veins as an exclusively centripetal system returning blood to the heart.
A much earlier predecessor was Ibn-Nafis (c. 1210-80), who also postulated the existence of the pulmonary circulation, but there is no evidence that Servetus knew of him. Although Alpago translated Ibn-an-Nafis in the Renaissance, he apparently failed to deal with the writings pertaining to pulmonary circulation.
Nevertheless, it was William Harvey who worked out most of the problems and is responsible for the present understanding of the blood’s circulation. After being educated at Cambridge, he went to Padua, the apex of medical teaching at the time, where he found a direct link to Vesalius. Gabriello Fallopio (1523-62), after whom the Fallopian tubes are named, had been a pupil of Vesalius, and Fallopio was the teacher of Fabricius ab Aquapendente (1537-1619), one of the giants at Padua, who was in turn Harvey’s teacher. The description by Fabricius of the valves in the veins was an important observation which Harvey used to support his circulation theory.
After returning to England from Padua in 1602 Harvey entered medical practice in London. There he rose quickly. Elected to the London College of Physicians, he gained a wide reputation and even became a court physician, first to King James I and later to King Charles I. During his many years as a practicing clinician in the monarchy, Harvey had managed also to engage in research. Although his lecture notes show that he believed in the circulation of the blood as early as 1615, he did not publish his findings until thirteen years later in Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (On the Movement of the Heart and Blood in Animals), one of the most important works in medicine and biology.
How did Harvey reach his conclusions? For one thing, he concerned himself solely with the mechanical flow of blood, not with what happened in the heart, liver, and brain. Nor was he involved with experiments on the role of the natural, vital, and animal spirits which were part of Galenic physiology. (Nevertheless, he continued to believe that the heart manufactured “vital spirit” which resided in the blood and was equivalent to the soul of man.) His arguments were based on morphological examples drawn from dissection and physiological experiments on animals. For instance, he showed that because of the valves in the heart and the veins, blood could flow in only one direction. In seeing that both ventricles of the heart contracted and expanded together, he concluded that there was no pressure difference between them which could drive blood through the thick septum. Moreover, the septum had its own system of arteries and veins, which would not be necessary if blood percolated through it. He also noted that after being removed from an animal, the heart continued to contract and expand like a muscle. Therefore, it was clearly a pump and not just an organ that sucked in blood. By experiment with a live serpent, Harvey demonstrated the direction of flow toward the heart in the great vein (vena cava) and away from the heart in the main artery (aorta).
In addition to anatomical dissections, physiological observations of humans, and direct experiments on animals, he also made use of quantitative data. If the human heart contained two ounces of blood (an observation from cadavers) and made about sixty-five beats per minute, then in one minute it pumped about eight pounds of blood. This amount multiplied by the minutes in a day gave a fantastic quantity of blood, far too much for the body to produce rapidly from food eaten. Harvey further supported these speculations with experiments on live sheep. Severing a sheep’s main artery he collected and measured the blood expelled in a unit of time. It became obvious to him that blood circulated in a closed system. For the connection between arteries and veins to complete the circuit, Harvey assumed that there were capillaries even though he could not see them. The discovery of these microscopic structures was accomplished after Harvey’s death by Marcello Malpighi (1628-94).
Although his contributions had enormous importance to anatomy and physiology, their impact on the practice of medicine was limited since the concepts and understandings of disease were little advanced by his demonstrations. However, after Harvey’s proofs that a person’s blood was continually recycling, the question of whether to bleed a patient from the same or opposite side of a disorder became irrelevant. Medicine adjusted to the circulation of the blood but still thought in terms of humors and of therapeutics relying on bleeding, purging, and vomiting.
Harvey’s work was an important confirmation of the new mechanical science and the principles of experimental and quantitative analysis. His work formed a common front with that of Galileo, Kepler, Newton, Boyle, Borelli, Malpighi, and others. In his lecture notes Harvey compared the heart to a water bellows or a pump, which helped support the growing success of mechanistic philosophy.
How was Harvey’s work received by his fellows? For twenty years after the publication of On the Movement of the Heart and Blood in Animals controversy raged over its conclusions. In this initial period many medical men ignored him, including those who had observed his demonstrations. For some of these men—surgeons concerned with achieving a respectable status denied them by the fraternity of physicians—adhering to Galenism made them more acceptable. His first major supporter was Robert Fludd (1574-1637), a mystic philosopher, physician, and friend who subscribed to the ancient concept of the human as a microcosmic analogy to the macrocosm. He concluded that the heart was the center of the body in the same way that the sun was the center of the universe. Another important champion of William Harvey was Jan de Waal (Walaeus) (1604-49), who performed new experiments that supported Harvey’s findings.
James Primerose, an extreme adherent to Galenist doctrines, was the first to attack Harvey’s ideas. He explained away the absence of pores in the septum of the heart by postmortem changes. Another critic was Caspar Hofmann (1572-1648). Although Hofmann was a supporter of Cesalpino and acknowledged the pulmonary transit (which he attributed to Realdo Colombo), he denied the muscular nature of the heart. He felt that Harvey had abandoned anatomy to the mathematical logic of calculation and quantitation. Hofmann also objected because Harvey’s theories seemed to show that nature was acting superfluously by constantly circulating the blood. Harvey’s response was simply that even if he did not know the reason for the circulation he saw that it happened.
Another critic of Harvey, Jean Riolan the Younger (1580-1657), an astute anatomist, tried to reconcile Harvey’s teachings with Galen’s. Using the same quantitative reasoning he arrived at a very different conclusion. By assuming that the heart pumped no more than a drop or two at each contraction, and by estimating how many drops were pumped each hour, he argued that no more than one or two circulations occurred per day. To account for Harvey’s observations, Riolan explained that the heart, in the process of dying during vivisection, allowed blood to accumulate and so appeared to pump more blood. To him Harvey’s results were therefore actually created by the experiments themselves.
Descartes also differed with Harvey. Earlier he had himself proposed a theory of the circulation of the blood, utilizing Aristotelian and Galenic notions. He accepted the idea of a continuous circulation in a contained system but hypothesized that vaporization of blood in the heart forced it to dilate.
As a logical extension of the information obtained from Harvey’s contributions, intravenous administration of drugs was introduced in the same century. Moreover, the first transfusions of blood into animals and then from animals into humans were also attempted with indifferent success and some outstanding failures.
The exact manner and careful experimentation of William Harvey has caused some historians to see him as a modern and to overlook the ancient prejudices he may have possessed. Others have seen Harvey as a representative of a strongly Aristotelian tradition and his quantitation as of only secondary importance. To them Harvey’s idea of the circulation of the blood did not come from experimentation but from his belief in the Aristotelian principles that circular motion was the most perfect type of action and that the heart was the center of life. However Harvey is evaluated, his contribution is one of the most important in the history of medicine.
ANATOMICAL AND PHYSIOLOGICAL ADVANCES
The story of the thermometer is an example of how clinical observation, physiological understanding, and technical development can intermingle in the achievement of a notable advance in medicine.
In the days of Hippocrates, the importance of body temperature was well recognized, but the physician had only his hand to evaluate the feel of a patient’s skin. Later, in Alexandria, a patient’s pulse became so important that body temperature was probably secondary. In the Middle Ages (because of the four humors and their qualities of hot, cold, dry, and moist), fever was considered a highly significant aspect of clinical observation even though scientific measurement of temperature was not attempted.
In 1592 Galileo constructed a thermometer (probably the first), but it gave only gross indications of temperature changes, had no scale of measurement, and was influenced by atmospheric pressure. Neither he nor his contemporaries appeared to see any medical application for the device. Santorio, however, showed a great interest in measuring body heat and devised ingenious but cumbersome thermometric instruments.
An essential step toward measurement was achieved in 1665 when Christiaan Huygens (1629-95) suggested a fixed scale in which the freezing point of water (designated as o degree) and the temperature of boiling water (100 degrees) were the parameters—the origin of the centigrade system. Gabriel Daniel Fahrenheit (1686-1736) in 1717 devised a scale which set the temperature of a mixture of ice and ammonium chloride as the lower fixed point and used smaller degree increments than in the centigrade scale. He found mercury more useful than water in his apparatus since its expansion and contraction are more rapid.
The first wide use of thermometry in clinical practice was by Hermann Boerhaave (1668-1738) in Holland and by his students Van Swieten and De Haen in Vienna. A voluminous study by De Haen reported the daily cyclical changes in the temperatures of healthy people, the rise in temperature produced by shivering, and the relationship of pulse to temperature. He emphasized the usefulness of temperature readings as a monitor of the course of illness, but most physicians of the day were not convinced. Not until about a century later did the thermometer become an integral part of medical practice.
The Swedish astronomer Anders Celsius (1701-44) in 1742 reintroduced the centigrade standard in clinical practice, and a series of improvements in the instrument and an increasing number of observations on the physiologic and pathologic significance of the temperature followed rapidly. Karl August Wunderlich (1815-77) by studying thousands of cases intensively was able to augment the realization that fever was a symptom, not a disease, and that the temperature of the patient was at least as important as the pulse. Yet many physicians still neglected to take temperatures, and some even scoffed.
Much of the resistance by practitioners was due to the complexities of measuring the temperature. The early thermometer was long and cumbersome and sometimes had to be maintained in contact with the patient for twenty-five minutes at a time. Aitkin in 1852 made the instrument more practical by narrowing the glass tubing above the bulb so that the column of mercury did not fall back again when the thermometer was removed from the patient. Finally, Thomas Clifford Allbutt in 1870 designed the size and shape employed today.
One of the most important inventions in the development of medicine and general science was the microscope. The use of a ground lens as a magnifying glass was known in antiquity, and eyeglasses had been made in the Middle Ages. A Dutch spectacle-maker, Zacharias Janssen, and his son introduced the combination of more than one lens to increase power, but these earliest microscopes were crude and achieved a magnification of no more than ten times. The first scientific treatise making use of the microscope was done by Francisco Stelluti on the structure of the bee and was published in Rome in 1625. Pierre Borel may have made the first use of the microscope for medical inquiry. In 1655 he referred to wormlike creatures he saw in the blood of patients with fevers, but whether this was merely a fanciful elaboration of ancient views is not known. The two giants of seventeenth-century microscopy were Marcello Malpighi (1628-94) and Antony van Leeuwenhoek (1632-1723).
Leeuwenhoek was a cloth merchant in Delft, Holland, but he used his spare time to make lenses for microscopes so efficient that they were unsurpassed until the nineteenth century. Self-taught, and without Latin, he had difficulty keeping informed on scientific developments. Yet, eventually he was able to produce microscopes with a magnification power of 270 times. Before his death he had accumulated four hundred microscopes, some of which he bequeathed to the Royal Society in London, where he had sent the reports of his observations.
Leeuwenhoek looked through his microscope at everything imaginable, and his reports led the way to extraordinary advances. He was the first to recognize the blood corpuscles (which Malpighi had identified as “fat globules”). He also made a thorough study of spermatozoa and noted the striped appearance of skeletal muscle.
Malpighi, regarded as the founder of biological microscopy, also reported his findings in brief letters to the Royal Society in London. His contributions in both botany and biology affected the entire science of microscopy. By developing techniques for preparing tissues to be examined under the microscope, he and his successors were able to make observations otherwise impossible. Malpighi was the first to confirm by microscopic examination of the lungs the capillaries which Harvey postulated. He also corrected the previous view that the lungs were of a muscular consistency by showing that they consisted of many extremely thin-walled compartments connected to the smallest branchings of the windpipe. Indeed, hardly an organ escaped his discerning eye.
Many other advances were made in understanding the anatomy and physiology of the body. Francis Glisson (1597-1677) described in detail the liver, stomach, and intestines. Although his general biological views were basically Aristotelian, he also had modern ideas, as for instance that nerve impulses cause the evacuation of the gallbladder.
Thomas Wharton (1614-1673) in giving a comparative account of the glands took an important step by denying the old and persistent idea that the brain was a gland which secreted mucus. (However, he continued to believe that tears originated in the brain.) Wharton described the distinguishing characteristics of the digestive, lymphatic, and sexual glands, and the exit canal of the submaxillary salivary gland is now known as Wharton’s duct. A highly significant contribution was his recognition that there were ductless glands (now called endocrine glands) whose secretions entered the blood, as distinguished from ductile glands whose secretions were discharged into cavities (exocrine glands). Niels Steensen in 1661 made clear the distinction between these glands and the lymph nodes (which are sometimes still called “glands” although not part of the glandular system). He also disproved the belief that tears came from the brain.
The increased knowledge of the transport systems of the body attained through the work of a number of investigators helped to resolve the misconceptions of Galenic physiology concerning the production of blood. Gasparo Aselli (1581-1626) discovered that after a substantial meal the peritoneum (lining of the abdominal cavity) and the intestines of a dog became covered by white threads, from which a white fluid oozed when cut across. These vessels were the lacteals (the lymph channels of the intestines). Further details were clarified by Johann Vesling, Jean Pecquet, Thomas Bartholin, and Olof Rudbeack, who fought among themselves for recognition as pioneers.
Up to the time of Harvey, it was believed that respiration was meant to cool the heart for the production of vital spirits in the right ventricle. Though Harvey demonstrated that in the lungs blood was changed from venous to arterial, the basis for the change was unknown. The function of respiration took years for clarification, but there were notable increases in understanding during the seventeenth century. Boyle’s experiments proved that both the combustion of a candle and the life of an animal were sustained by air. Robert Hooke (1635-1703) demonstrated that even without chest movement an animal could survive as long as air was pumped into the lungs. Richard Lower (1631-91), the first to transfuse blood directly, showed that the color difference between arterial and venous blood was due to contact with air in the lungs. John Mayow (1640-79) indicated that this reddening of venous blood happened because something was taken out of the air. He came close to a realization that respiration is an exchange of gases between the air and blood, believing that air gave up its “nitro-aerial spirits” and took away vapors yielded by the blood.
The Nervous System
In 1664, Thomas Willis (1621-75) published in De Anatome Cerebri what was then probably the most thorough summary of the nervous system. His anatomical and physiological studies led to the use of his name in connection with the circle of arteries at the base of the brain, the eleventh cranial nerve, and also a type of deafness. However, in his zeal to localize mental processes anatomically, he drew unwarranted conclusions; among them, that the cerebrum controlled the motions of the heart, lungs, stomach, and intestines and that the corpus callosum (a tract connecting the brain hemispheres) was the site of the imagination.
Few of the anatomical and physiological discoveries of the period were seen as useful to practical clinical medicine. Even the great Thomas Sydenham (1624-89), possibly the century’s most famous clinical leader, placed little emphasis on the recent advances in science and medicine. Although he may have known of Harvey’s blood circulation hypothesis, he would not have considered it medically useful, believing instead that observational skills and experience were far more valuable than scientific theories. He saw no practical value in microscopic anatomy, reserving his interest for visible anatomy readily correlated with the patient’s state of health.
Sydenham has been called the “English Hippocrates.” His detailed descriptions of gout, influenza, measles, scarlet fever, and other conditions were masterful, and his attention to bedside medicine rather than to books was in the Hippocratic tradition. He taught that each patient was a unique dynamic entity in whom a disease could vary from person to person, but, unlike Hippocrates, he did concern himself with classifying diseases. Classification, however, became far more characteristic of the next century, when Linnaeus and others developed detailed categorizations of plants and animals.
As a follower of Francis Bacon, Sydenham also collected random scientific observations until he could induce a generalization. Nevertheless, while he supported the idea of experimentation, he preferred to reason out the causes of disease, using his senses to gather clues. Ultimately, to him, health or illness depended on the adequacy or foulness of the air, the sufficiency and character of food, the amount of exercise, rest, sleep, and alertness, the retention or evacuation of body fluids, and the calmness or perturbations of the mind. Sydenham’s reputation was enormous, as was his influence on practice.
Another great clinician, Thomas Willis, was more in tune with the new methods of science, since his views were for the most part arrived at by experiment. For instance, to understand nerve function he tied off the vagus nerve in a live dog and observed the effects on its heart and lungs. To match clinical symptoms with anatomical abnormalities (pathology), he performed many autopsies. He was also one of the first to emphasize the sweetness of urine in diabetes, thus differentiating it from another unrelated condition formerly called diabetes insipidus.
The seventeenth century was not an innovative period in medical education. Anatomy was inadequately presented, and most teachings were dependent on works of antiquity or the writings of Muslim authors such as Avicenna. Standards and requirements for medical students varied greatly from country to country and even within a country. Degrees from Leiden which could be bought after a brief visit of a few weeks were nevertheless honored at Cambridge. Students were frequently disrespectful and rowdy, and it was during this century that much of the influence of students in shaping the curriculum and controlling the operation of universities began to wane.
In France three kinds of medical degrees were given: the baccalaureate, the license, and the doctorate—with different privileges attending each degree. The pattern was similar in other European countries and England. Sometimes a Bachelor of Arts degree (or equivalent) was a prerequisite to entering medical training, and so it might take thirteen years to complete a doctorate. Most medical students came from the middle class, and, while entrance into medical training was relatively easy for sons of physicians, prohibitions were stiffened against nonconverted Jews, bastards, and sons of hangmen. Among the upper classes, generally it was the petty nobility rather than the highly placed who entered the profession. They were well-paid and socially recognized as part of the intellectual elite, but the passing of medical examinations was often mainly a demonstration of competence in Latin.
In France, of the twenty-four medical schools four were dominant: Montpellier, Paris, Toulouse, and Strasbourg. Montpellier, one of the oldest, imparted the most classical education, but it was also more intellectually free and independent of the church than the Paris school. Some countries of Europe had many medical schools, while others such as the Netherlands (which from 1580 to 1625 graduated approximately three students per year) had few. In Russia, for many centuries the only physicians available had been trained abroad and usually ministered only to the nobility and the court. The majority of the population was treated by monks, women who knew the medicinal value of plants, and lay surgeons who treated wounds. At the beginning of the seventeenth century there were approximately twenty physicians in all of Russia trained in Western methods. However, responding to the need for more physicians to treat the wounded and sick of the Russo-Polish war, Czar Alexei Mikhailovich (1645-76) finally created a medical school. In the British Isles, Italy, Germany, and Spain, there had been universities since the Middle Ages.
Scientific progress in the seventeenth century came less from the universities than from new public and private scholarly societies. Whereas the universities were Aristotelian in outlook, that is, deductive and backward-looking, the scientific societies were experimental, inductive, and empirical. The Accademia dei Lincei (Academy of the Lynx) evolved in Rome in the early part of the century as a discussion group, which included Galileo among its members. The first truly empirical society was the Accademia del Cimento (Academy of Experiment) in Florence, in which the members worked together on questions of an experimental nature. They published their first work in 1667. Informal scholarly groups in other parts of Europe gradually arose. Initially scientific discoveries had been propagated through correspondence, but eventually a few journals, such as the very important Philosophical Transactions of the Royal Society in England, were created to disseminate this information.
England and France took different approaches to scientific societies. In France, the Academie des Sciences, which had only a small membership, was founded to bring together the leading scientists of France and the world. The French government appointed the members and paid their salaries. They were the best-equipped scientists in Europe, but their arrangement had a price, for the government had a controlling influence. In England, the Royal Society was organized as a public group with little but moral support from Charles II, its doors open to anyone who showed an interest in scientific endeavors. However, amateurism among the membership in the 1670s almost caused the society’s collapse, but it survived and today may be the oldest scientific society still in existence.
Besides the Royal Society, of which physicians made up the largest group, there was an entirely separate College of Physicians, whose functions included policing the profession, controlling quackery, regulating competition from other medical groups such as the apothecaries, overseeing fees, and limiting personal feuds between physicians. Whereas the College of Physicians was parochial, the Royal Society had numerous foreign members including Leeuwenhoek and Malpighi. There was an extraordinary openness with respect to research and medical information in the society, and its Philosophical Transactions was circulating at a time when special remedies and medical techniques were often kept secret.
An interesting overview of the medical profession in the seventeenth century may be obtained by noting the conflicts between apothecaries and physicians in London. By 1617, apothecaries had dissociated themselves from grocers and formed their own society. Originally apothecaries were restricted to filling prescriptions exactly as physicians ordered, but they could perform bleeding. While physicians wished to maintain the status quo, the apothecaries sought to liberalize the restrictions. By the end of the seventeenth century the apothecaries had overcome the opposition and were permitted to practice medicine—without a physician’s license. But the battle was bitter and stormy.
Because of the relative paucity of educated, licensed doctors, apothecaries filled a void, often performing the treatments physicians had advised after examining the patient. However, to prevent a patient from relying too much on an apothecary, the practitioner sometimes wrote a prescription without directions for its use, giving these only to the patient. Apothecaries retaliated by favoring with referrals only those doctors who would prescribe large numbers of drugs, since apothecaries were not permitted to charge a fee for direct advice. The culmination of the antagonism occurred in 1704 when an apothecary who had brought charges against a butcher for nonpayment for medical services won his case, after a turbulent legal battle and an appeal. Apothecaries thereby emerged as sanctioned general practitioners.
Dentistry was practiced by any who could acquire the skills. Although there were legitimate doctors, barber-surgeons, and apothecaries who could take care of teeth, many quacks also posed as tooth-drawers and often displayed their techniques in the street before audiences of passersby. In 1699 an edict of Louis XIV established the professional status of dentists in France. Two years of study were required, followed by an examination before the College of Surgeons on theory and practice. In addition a special category was created for surgeon-dentists, that is, surgeons who had specialized in dentistry.
Although doctors were generally held in high regard, the limitations of medicine and the arrogance of some of its practitioners did not escape the biting satire of cartoonists and writers. Moliere, for example, exposed the petty frailties of physicians in his plays. Ironically, in Moliere’s last performance as an actor, in The Imaginary Invalid, his uncontrollable coughing—associated with tuberculosis—was applauded by the audience as brilliant acting. Shortly after, the great playwright-actor expired. The helplessness of the medical profession in treating Moliere’s illness may have contributed to his scornful attitudes.
Therapy in the seventeenth century was mainly a continuation of the past in terms of bleeding, purging, dietary restriction, exercise, and the use of nonspecific plant, mineral, and animal drugs. One new medication, however, was a striking departure in effectiveness and in general influence on the principles of therapy: quinine—as a treatment for malaria.
Malaria affected much of Europe and had been a disease of considerable impact in all centuries. In the seventeenth century, it was still called “ague,” and not until the eighteenth century did its present name (from mal aria, “bad air”) become common because of the disease’s association with swamps. The first effective remedy for it, a plant derivative from Peru, was called cinchona by Europeans because of a fanciful story that the Spanish countess of Cinchon had introduced the plant into Spain from Lima, where her husband the viceroy was supposed to have been cured by the “fever bark.” Apparently cinchona was introduced into Europe about 1633 after having been cited by Antonio de la Calancha as a substance that “produced miraculous results in Lima.” Word of the medicinal bark spread rapidly, as did demand for it. Because Jesuit priests held a virtual monopoly on its importation into Spain and Italy, it was also called “Jesuit’s Bark.”
The introduction of cinchona had an enormous influence on venerable concepts of illness. At the time malaria had been a chronic disease that took many months to alleviate, but since cinchona cured quickly and acted specifically on only a certain kind of fever, the belief in fever as a general manifestation of unbalanced humors received a severe blow. It was then felt that each fever could be a different disease. In modern times, we have returned to the idea of fever as a general manifestation of various different specific illnesses.
Quinine was isolated from cinchona in the first quarter of the nineteenth century and received its present name from the quina-quina plant, which, although it had no antimalarial properties, had been mistaken for cinchona. Quinine remained the only effective antimalarial until well into modern times. However, many knowledgeable physicians continued to use the ancient arsenical preparations because they were thought to produce a more permanent cure and also because cinchona cost so much. Indeed, arsenic salts were to continue for centuries as mainstays in therapeutics. Even those who appreciated the dangers still used arsenic confidently, though cautiously, for a multitude of external and internal conditions. Well into the nineteenth century, an arsenic compound called Fowler’s solution became so popular that it was mocked in cartoons.
Surgery in the seventeenth century did not keep pace with the progress in anatomy and physiology. The means for making surgery safe—anesthesia and control of infection—had not yet arrived. Nor did surgeons reach the social and academic level of physicians. One exception was Charles-Francois Felix, who operated successfully on an anal fistula of Louis XIV and gained for surgery the support of the crown. Nevertheless, French surgeons alternately competed with barbers and then joined with them against the physicians, as English surgeons had done in the previous century.
There were two kinds of surgeons and various grades within the subdivisions. “True” surgeons concerned themselves with the major operations: suture of holes in the intestines, removal of tumors, plastic operations on the lips and nose, repair of rectal fistulas. The barber-surgeons were wound doctors who also performed bloodletting, cupping, the extraction of teeth, and the management of fractures, dislocations, and external ulcers. In addition, there were untutored, itinerant wound-doctors who operated for cataracts, bladder stones, and hernias—apparently with results so bad that reputable surgeons avoided association with them.
The names of a few surgeons should be mentioned. In Italy, Cesare Magati (1579-1647) followed Pare’s teachings that gunshot wounds should be treated by plain water and mild applications rather than with the cautery or boiling oil. Pietro de Marchette reported many complex case histories, and Giuseppe Zambeccari was a pioneer in experimental surgery. Peter Uffenbach compiled a noteworthy surgical anthology which relied exclusively on the practices of sixteenth-century surgeons. Johann Schultes (1595-1645) was a great illustrator of surgical treatises. Matthaeus Gottfried Purmann (1649-1711) emphasized the anatomical basis of surgery.
Wilhelm Fabry of Hilden (1560-1634), considered the “Father of German Surgery,” was an innovator and one of the first to emphasize amputation through healthy tissue rather than the gangrenous part. Yet he continued to utilize the cautery and to rely on “weapon salve,” an accepted method of the time whereby the medicament was applied to the weapon rather than the injured part. This idea seemed to fit the new atomism, which saw the weapon, especially gunpowder, as giving off atoms of the same material it had deposited in the wound. In a manner of “like attracting like,” the atoms of the weapon together with the medication would be brought to the wound. This method, fanciful as it was, nevertheless may have been beneficial to the patient since the wound was spared frequent applications of ointments and injurious substances.
Male attendants had rarely been present at the birth of a child, but by the end of the seventeenth century male midwifery had become the fashion in certain parts of Europe. In 1628 Peter Chamberlen attended Queen Henrietta Maria in a miscarriage, and in 1692 another Chamberlen was responsible for delivering a child to the future Queen Anne. The Chamberlen family had a secret obstetrical forceps which was guarded carefully and was thought to be the reason behind their successful results. More and more, men began to assist in delivery and to take an active part in the medical supervision and examination of women.
The attitude of the period toward mental illness continued to be ambivalent. Felix Platter (1536-1614) categorized insanity as follows: imbecilitas, consternatio (febrile delirium and catatonic states), alienato (dementia, alcoholism, love and jealousy, melancholia and hypochondriasis, possession by the devil, raving mania, St. Vitus’s dance, and “phrenitis”), , and defatigatio (insomnia which was supernaturally caused by God or the devil).
Belief in witches continued to decline, but it was not until 1680 in France that the death penalty for being a witch was abolished. As supernatural causes were gradually abandoned, the mentally ill came to be considered merely “asocial.” However, one bad effect of this notion was their incarceration along with criminals and paupers.
The new technique of transfusing blood was extended by Jean-Baptiste Denis (1620-1704) to the treatment of mental patients. When arterial blood of lambs was injected into the venous system, the patients seemed to recover. However, when one patient died, the method was discontinued.
The quackery of the time, which seemed to become ever more common, was in part due to the bitter controversies between the Paracelsians and Galenists, who reviled each others as “quacks,” and to the obvious failure of even reputable physicians to stem the course of the epidemics which recurred frequently.
The state of concern for public health in seventeenth-century England may be amply illustrated in the care of children. Many unwanted sons and daughters were simply abandoned, and they roamed the streets in bands. Youngsters of four or five were frequently put into workhouses, and older orphans might be shipped to America. It seems that children of the poor had little or no access to medical attention. Of the many texts available on treatment and rearing of children, one of the most popular was actually written in Roman times—the work of Soranus.
Epidemics of plague, measles, smallpox, scarlet fever (carefully defined by Sennert but nevertheless confused with measles), chicken pox (“swine pox” on the bills of mortality), diphtheria (under various names), and other acute febrile illnesses took an especially heavy toll of the young. Congenital syphilis first appeared in a pediatric text during this time, to join gonorrhea, scurvy, lumbago, and rickets as diseases believed to be transmitted by inheritance. Infants with syphilis were often abandoned by everyone (including their mothers) because of the fear of transmission—especially to wet nurses, who frequently passed from infant to infant. Among the well-to-do, wet nurses were carefully chosen since it was believed that breast milk could influence the health and behavior of the young.
Tongue-tie was treated by midwives, who grew the right thumbnail long to cut the frenulum. Ear infection (otitis), since it occurred so frequently, was considered virtually a normal condition, as were discharges from the nose and ears which were presumed to issue from the brain. Dental diseases sometimes caused death, and “worms” were implicated when another diagnosis was not apparent—an idea with an ancient history. In addition, congenital and acquired blindness were common.
Nor were health conditions much better for adults. In some places, epidemics of the plague killed over half the population: 80,000 in Milan and 500,000 in Venice. Furthermore, the Thirty Years War was devastating to life and hygienic conditions, especially in Germany. Organization and administration of public health controls remained virtually the same as in medieval times. Whatever organization there was centered around the towns, for the leaders had begun to recognize that a healthy population was beneficial to the state.
There was a start at gathering some health and vital statistics in the sixteenth century, but significant attention to the statistical analysis of medically related phenomena only developed in the latter half of the seventeenth century. In England, at the beginning of the century, christenings, marriages, and burials were recorded by local parishes, and this information was passed to the king on a weekly or annual basis. In 1629 these “bills of mortality” were expanded to include fatal diseases other than the plague.
Generally the medical profession had little interest in statistics. The collection and analysis of everyday numbers did not at first seem to them valuable in the treatment of patients. Indeed the first person to utilize medical statistics was a tradesman, John Graunt (1620-74), who was also a ward politician. The spirit of quantitation which began to pervade scientific thinking, however, finally influenced many medical leaders to see the importance of the numbers. Graunt ‘s book, Natural and Political Observations… made upon the Bills of Mortality (1661), analyzing and evaluating the bills over a sixty-year period, so impressed the medical fraternity that Graunt was admitted to membership in the august Royal Society, a particularly signal honor for a layman.
One of Graunt’s supporters was Sir William Petty (1623-87), who had helped him with his book. Since Petty believed that a large population was an asset to a country, he favored all measures which preserved and restored health. He saw that hospitals should be the focal point not only for treating the sick but also for training physicians and developing research. He offered many brilliant, far-reaching proposals, such as separate hospitals for plague victims, specialized maternity institutions, governmental concern for the health of occupational groups, and the establishment of a central health council to organize public health. However, these measures were too far in advance of the times, and very few of Petty’s suggestions were then carried out.
Graunt’s ideas, however, did have important influences. In 1669 Christiaan Huygens and in 1693 Edmund Halley (1656-1742) used their mathematical talents to arrive at tables of life expectancy, which later would be of use in life insurance. Of course statistics worked into medical thought from other sources besides Graunt: the collection of meteorological information, the popular accent on mathematics, the interest in precision instruments, and the beginnings of experimental data on physiological phenomena.
The growing concern of the state for its citizens was especially exhibited by the German principalities, where the concept developed that government through its agents was responsible for the care and supervision of its citizens in regard to disease.
In several areas of Europe, public health remained primarily the responsibility of the inhabitants (for example, street cleaning and drainage), but laws were created and inspectors were assigned for enforcement. “Scavengers” were appointed to collect the garbage, and space outside of town was assigned for the dumping.
Town water resources initially were springs and wells, and later the rivers. When technical innovations such as pumps gradually came into public service, water was usually conveyed to a central cistern and from there to local cisterns; however, most of it was polluted by the time it reached the consumer.
Hospitals for the crippled were a local responsibility and usually were intended for the care of the poor, the aged, and the sick. The adaptation of hospitals for their separate task of treating the acutely ill did not occur until the eighteenth and nineteenth centuries, but in the seventeenth century hospitals began to be used for medical research and teaching.
Among the outstanding contributors of the time to public health were Lancisi, Kircher, and Ramazzini. Giovanni Maria Lancisi (1654-1720) came close to understanding that an insect transmitted malaria, believing that swamps emitted animate creatures (later found to be mosquitoes) and also inanimate particles that produced disease.
Athanasius Kircher (1601-80) was among the first to point explicitly to microorganisms as the cause of infectious disease. However, it is likely that the “worms” he saw in the blood with his low-power microscope were actually red cells and not bacteria. His work attracted attention throughout Europe, but because of technical and theoretical difficulties some followers fancifully reported seeing more than actually existed—which caused a reaction that led to a general condemnation of claims that disease was due to microscopic creatures.
Bernardino Ramazzini (1633-1717) wrote the first full-scale treatise on occupational health, which examined the potential sources of illness in more than forty-two different occupations, including those of miner, gilder, midwife, apothecary, singer, painter, soldier, and baker. Ramazzini’s work was an important synthesis of all the knowledge then available on occupational disease and served as a source for further investigation by students of public health until the nineteenth century.