§5. Medicine in Alexandria

Pre-Platonic philosophers initiated physiology research, including Pythagoras, Alcmaeon, Empedocles, and Democritus. Aristotle added more, but then interest among philosophers in physiology melted, leaving physicians with the field to themselves.

Hippocratic doctors did not practice human dissection. A scholar of an­cient medicine observes that for “the vast majority of physicians in antiq­uity... cutting open a deceased human being was virtually unthinkable.” It first became usual in Alexandria from the third century bce, and quickly produced a flood of new knowledge, including the differentiation of motor and sensory nerves, veins and arteries, and new ideas about digestion and vascular flow. Erasistratus observed the operation of valves in the heart, whose mechanism he demonstrated but whose function baffled him. He held the view that veins alone contained blood, arteries supposedly being conduits of the colorless pneuma. He thought arterial and venous systems were separate, so why does the heart need valves? He decided it was to pre­vent reflux as the heart expands and contracts, though why it expanded and contracted so vitally was a mystery too, especially when Erasistratus knew that heartbeat had nothing to do with pulse, which was a contraction of the veins themselves, independent of the heart.

Details of medicine in Alexandria remain elusive. The efflorescence of sci­entific medicine in the city has been attributed to exposure to native Egyptian medicine, and while little is known of Egyptian medicine at this time, sugges­tive parallels do exist, especially touching medical empiricism. Since it was at this time that Greek doctors began conducting postmortem autopsies, it is interesting that Egyptian embalmers were included among physicians, and postmortem surgery was a regular feature of their medicine. Egyptian physicians had an advanced teaching on pulse, which emphasized counting and measuring. That was not the Hippocratic perspective, which was quali­tative and took little notice of numerical difference. Referring to Herophilus’s use of a portable, adjustable water clock to measure pulse, Heinrich von Staden observes, “It is not inconceivable that the sophisticated Egyptian water clock technology, the Egyptian interest in quantification... and the keen interest of Greek Alexandrians in technology and gadgetry all com­bined to prompt or facilitate Herophilus’s introduction of his measuring device.”³⁸

Further evidence comes from Egyptian pharmacology and materia medica, once again in a context touching medical empiricism. Hippocratic prescriptions are notoriously vague about quantity, whereas Egyptian medi­cine is self-consciously and technically precise. From Herophilus in the third century, medical empiricists became meticulous in their specification of measures, an advance over Hippocratic medicine that has left a trace in med­icine today, where our Rx symbol for pharmaceuticals derives from the Eye of Horus, the symbol used by Egyptian doctors for the same notion.

Working in Alexandria, Herophilus made many advances in anatomy. His works include an anatomy of the brain, which first identified the major ventricles; and the discovery of the two kinds of nerves, which he named aisthetika (sensory) and prohairetika (purposive, choosing), proving for the first time that one “nervous system” is responsible for voluntary move­ment and sensation. He wrote classic descriptions of the eye and liver, and first identified the duodenum and ovaries. Despite this searching empiri­cism, Herophilus was repeatedly attacked by the Empiricists, apparently for his view that certain invisible causes can be apprehended by inference from appearances.⁴⁰

Evidence attests to his use of causal explanation in both physiology and pathology. Polybius attributed the origin of “theoretical medicine” to his Alexandrian followers. Galen says Herophilus taught the use of “abstract reasoning” (logismos), though elsewhere he says he emphasized observation and emperia at the expense of a rational method and made “the examination of appearances” the basis of his statements. Galen says Herophilus “expressed doubt about every cause with many strong arguments.” A fragment attributes to him the statement, “Let the appearances be described first even if they are not first.” The idea is thought to come from Aristotle, whose biological treatises recommend, “First, the phenomena must be grasped... then their causes discussed.” Herophilus acknowledges relevant unobservables, though he is not as sanguine as Aristotle about knowledge of causes, as another frag­ment in Galen attests: “Whether or not causes exist is by nature undiscover- able, but it is on the basis of a supposition that I think that cooling, heating, and being replenished occur.” Conjectural ex hypothesi causal explanations

may have been too much for the Empiricists, but it was also a departure from Aristotle’s idea of science (§14).⁴¹

From our earliest report of the controversy, we learn that the term “em­piricist” was their own invention.

Celsus did not entirely endorse medical empiricism, though he seems to understand it well and agrees that the empirical doctors made a good point to insist on the physician’s experience. “It does not matter what produces the disease, but what relieves it.... We have no need to inquire in what way we breathe, but what relieves labored breathing............................................ All this is to be learnt

through experiences (cognosci experimentis)” However, when radical empiricists deny that something hidden from observation can be known at all, and refuse to be instructed by dissection (a doctrinaire phenomenalism that dogs empiricism down to the twentieth century), they go too far.⁴³

The Alexandrian empiricists apparently dismissed postmortem anatomy with the argument that death changes the body, rendering observations on a corpse otiose. Celsus thought autopsy offered physicians the opportunity to gain invaluable knowledge for the treatment of disease, making an argu­ment from the intuition at empiricism’s heart against an empiricism grown overly philosophical. “Without knowledge of the nature of things, medicine is stunted and weak,” that is, not just theoretically disabled but compromised in therapeutic efficacy.⁴⁴

Galen responds to empiricism the same way a century later, chastising the Alexandrian empiricists for their neglect of dissection, yet with arguments that respect their epistemological scruple. “If a man is ignorant of the posi­tion of a vital nerve, muscle, or important artery or vein, he is more likely to be responsible for the death, than for the saving, of his patient.” Galen praised anatomy both as research essential to understanding how the body works and as good practice for surgery. The unity of all sides of the medical art is his constant theme. A doctor cannot just be a doctor and not also a surgeon as well as a natural philosopher.⁴⁵