The first known Greek medical school opened in Cnidus in 700 BC. Alcmaeon, author of the first anatomical work, worked at this school, and it was here that the practice of observing patients was established. Ancient Greek medicine centered around the theory of humours. The most important figure in ancient Greek medicine is the physician Hippocrates, known as the "Father of Medicine", who established his own medical school at Cos. Hippocrates and his students documented many conditions in the Hippocratic Corpus, and developed the Hippocratic Oath for physicians, still in use today. The Greek Galen was one of the greatest surgeons of the ancient world and performed many audacious operations—including brain and eye surgeries— that were not tried again for almost two millennia. The writings of Hippocrates, Galen, and others had a lasting influence on Medieval European medicine and Islamic medicine, until many of their finding eventually became obsolete from the 14th century onwards.
Despite their known respect for Egyptian medicine, attempts to discern any particular influence on Greek practice at this early time have not been dramatically successful because of the lack of sources and the challenge of understanding ancient medical terminology. It is clear, however, that the Greeks imported Egyptian substances into their pharmacopoeia, and the influence becomes more pronounced after the establishment of a school of Greek medicine in Alexandria.
A towering figure in the history of medicine was the physician Hippocrates of Kos (ca. 460 BC – ca. 370 BC), considered the "father of modern medicine." The Hippocratic Corpus is a collection of around seventy early medical works from ancient Greece strongly associated with Hippocrates and his students. Most famously, Hippocrates invented the Hippocratic Oath for physicians, which is still relevant and in use today.
The existence of the Hippocratic Oath implies that this "Hippocratic" medicine was practiced by a group of professional physicians bound (at least among themselves) by a strict ethical code. Aspiring students normally paid a fee for training (a provision is made for exceptions) and entered into a virtual family relationship with his teacher. This training included some oral instruction and probably hands-on experience as the teacher's assistant, since the Oath assumes that the student will be interacting with patients. The Oath also places limits on what the physician may or may not do ("To please no one will I prescribe a deadly drug") and intriguingly hints at the existence of another class of professional specialists, perhaps akin to surgeons ("I will leave this operation to be performed by practitioners, specialists in this art").
Hippocrates and his followers were first to describe many diseases and medical conditions. He is given credit for the first description of clubbing of the fingers, an important diagnostic sign in chronic suppurative lung disease, lung cancer and cyanotic heart disease. For this reason, clubbed fingers are sometimes referred to as "Hippocratic fingers". Hippocrates was also the first physician to describe Hippocratic face in Prognosis. Shakespeare famously alludes to this description when writing of Falstaff's death in Act II, Scene iii. of Henry V.
Hippocrates began to categorize illnesses as acute, chronic, endemic and epidemic, and use terms such as, "exacerbation, relapse, resolution, crisis, paroxysm, peak, and convalescence." Another of Hippocrates's major contributions may be found in his descriptions of the symptomatology, physical findings, surgical treatment and prognosis of thoracic empyema, i.e. suppuration of the lining of the chest cavity. His teachings remain relevant to present-day students of pulmonary medicine and surgery. Hippocrates was the first documented chest surgeon and his findings are still valid. The Hippocratic Corpus contains the core medical texts of this school. Although once thought to have been written by Hippocrates himself, today, many scholars believe that these texts were written by a series of authors over several decades. Since it is impossible to determine which may have been written by Hippocrates himself, it is difficult to know which Hippocratic doctrines originated with him.
Temples dedicated to the healer-god Asclepius, known as Asclepieia (Greek: Ασκληπιεία, sing. Asclepieion Ασκληπιείον), functioned as centers of medical advice, prognosis, and healing. At these shrines, patients would enter a dream-like state of induced sleep known as "enkoimesis" (Greek: ενκοίμησις) not unlike anesthesia, in which they either received guidance from the deity in a dream or were cured by surgery. Asclepeia provided carefully controlled spaces conducive to healing and fulfilled several of the requirements of institutions created for healing. In the Asclepieion of Epidaurus, three large marble boards dated to 350 BC preserve the names, case histories, complaints, and cures of about 70 patients who came to the temple with a problem and shed it there. Some of the surgical cures listed, such as the opening of an abdominal abscess or the removal of traumatic foreign material, are realistic enough to have taken place, but with the patient in a state of enkoimesis induced with the help of soporific substances such as opium.
The ancient Greek philosopher Aristotle was the most influential scholar of the living world from antiquity. Though his early natural philosophy work was speculative, Aristotle's later biological writings demonstrate great concern for empiricism, biological causation, and the diversity of life. Aristotle did not experiment, however, holding that items display their real natures in their own environments, rather than controlled artificial ones. While in physics and chemistry, this assumption has been found unhelpful, in zoology and ethology it has not, and Aristotle's work "retains real interest". He made countless observations of nature, especially the habits and attributes of plants and animals in the world around him, which he devoted considerable attention to categorizing. In all, Aristotle classified 540 animal species, and dissected at least 50.
Aristotle believed that intellectual purposes, formal causes, guided all natural processes. Such a teleological view gave Aristotle cause to justify his observed data as an expression of formal design; for example suggesting that Nature, giving no animal both horns and tusks, was staving off vanity, and generally giving creatures faculties only to such a degree as they are necessary. In a similar fashion, Aristotle believed that creatures were arranged in a graded scale of perfection rising from plants on up to man; : the scala naturae or Great Chain of Being. .
He held that the level of a creature's perfection was reflected in its form, but not foreordained by that form. Yet another aspect of his biology divided souls into three groups: a vegetative soul, responsible for reproduction and growth; a sensitive soul, responsible for mobility and sensation; and a rational soul, capable of thought and reflection. He attributed only the first to plants, the first two to animals, and all three to humans. Aristotle, in contrast to earlier philosophers, and like the Egyptians, placed the rational soul in the heart, rather than the brain. Notable is Aristotle's division of sensation and thought, which generally went against previous philosophers, with the exception of Alcmaeon. Aristotle's successor at the Lyceum, Theophrastus, wrote a series of books on botany—the History of Plants—which survived as the most important contribution of antiquity to botany, even into the Middle Ages. Many of Theophrastus' names survive into modern times, such as carpos for fruit, and pericarpion for seed vessel. Rather than focus on formal causes, as Aristotle did, Theophrastus suggested a mechanistic scheme, drawing analogies between natural and artificial processes, and relying on Aristotle's concept of the efficient cause. Theophrastus also recognized the role of sex in the reproduction of some higher plants, though this last discovery was lost in later ages..The biological/teleological ideas, of Aristotle and Theophrastus as well as their emphasis on a series of axioms rather than on empirical observation, cannot be easily separated from their consequent impact on Western medicine.
Following Theophrastus, the Lyceum failed to produce any original work. Though interest in Aristotle's ideas survived, they were generally taken unquestioningly. It is not until the age of Alexandria under the Ptolemies that advances in biology can be again found. The first medical teacher at Alexandria was Herophilus of Chalcedon, who corrected Aristotle, placing intelligence in the brain, and connected the nervous system to motion and sensation. Herophilus also distinguished between veins and arteries, noting that the latter pulse while the former do not. He did this using the experiment involving cutting certain vein and arteries in a pigs neck until the squealing stopped. In the same vein, he developed a diagnostic technique which relied upon distinguishing different types of pulse. He, and his contemporary, Erasistratus of Chios, researched the role of veins and nerves, mapping their courses across the body.
Erasistratus connected the increased complexity of the surface of the human brain compared to other animals to its superior intelligence. He sometimes employed experiments to further his research, at one time repeatedly weighing a caged bird, and noting its weight loss between feeding times. Following his teacher's researches into pneumatics, he claimed that the human system of blood vessels was controlled by vacuums, drawing blood across the body. In Erasistratus' physiology, air enters the body, is then drawn by the lungs into the heart, where it is transformed into vital spirit, and is then pumped by the arteries throughout the body. Some of this vital spirit reaches the brain, where it is transformed into animal spirit, which is then distributed by the nerves. Herophilus and Erasistratus performed their experiments upon criminals given to them by their Ptolemaic kings. They dissected these criminals alive, and "while they were still breathing they observed parts which nature had formerly concealed, and examined their position, colour, shape, size, arrangement, hardness, softness, smoothness, connection."
Though a few ancient atomists such as Lucretius challenged the teleological viewpoint of Aristotelian ideas about life, teleology (and after the rise of Christianity, natural theology) would remain central to biological thought essentially until the 18th and 19th centuries. In the words of Ernst Mayr, "Nothing of any real consequence in biology after Lucretius and Galen until the Renaissance." Aristotle's ideas of natural history and medicine survived, but they were generally taken unquestioningly.
Through long contact with Greek culture, and their eventual conquest of Greece, the Romans absorbed many of the Greek ideas on medicine. Early Roman reactions to Greek medicine ranged from enthusiasm to hostility, but eventually the Romans adopted a favorable view of Hippocratic medicine.
This acceptance led to the spread of Greek medical theories throughout the Roman Empire, and thus a large portion of the West. The most influential Roman scholar to continue and expand on the Hippocratic tradition was Galen (d. c. 207). Study of Hippocratic and Galenic texts, however, all but disappeared in the Latin West in the Early Middle Ages, following the collapse of the Western Empire, although the Hippocratic-Galenic tradition of Greek medicine continued to be studied and practiced in the Eastern Roman Empire (Byzantium). After 750 AD, Muslim Arab also had Galen's works in particular translated, and thereafter assimilated the Hippocratic-Galenic tradition, eventually making some of their own expansions upon this tradition, with the most influential being Avicenna. Beginning in the late eleventh century, the Hippocratic-Galenic tradition returned to the Latin West, with a series of translations of the Galenic and Hippocratic texts, mainly from Arabic translations but occasionally from the original Greek. In the Renaissance, more translations of Galen and Hippocrates directly from the Greek were made from newly available Byzantine manuscripts. Galen's influence was so great that even after Western Europeans started making dissections in the thirteenth century, scholars often assimilated findings that should have thrown Galen's accuracy into doubt, into the Galenic model. Vesalius' anatomical texts and pictures were, however, a major improvement on Galen's anatomy. William Harvey's demonstration of blood circulation was perhaps the first real blow to Galen's inaccurate ideas about blood circulation. Nevertheless, the Hippocratic-Galenic practice of bloodletting was practiced into the 19th century, despite its ineffectiveness and the extreme riskiness. The Galenic-Hippocratic tradition was only really replaced when the microscope-based studies of Louis Pasteur, Robert Koch, and others, which demonstrated that disease was not caused by an imbalance of the four humors, but rather by microorganisms such as bacteria.