There is little in the writings of Hippocrates of direct value to us to-day; yet while crude, imperfect, and visionary, they were of profound importance in the development of medicine. They constitute the first systematic literary presentation of pure medical science and art, aside from sacerdotal systems. They were, for the time, a very creditable beginning toward the development of rational medicine; and had progress in the subsequent ages been as substantial as that in the brief time prior to Hippocrates, the history of internal medicine for the ensuing two thousand years would not have been one of stagnation and inefficiency. Hippocrates showed himself to be a keen observer of clinical phenomena, a master clinician, and the part of his work of permanent value was the accumulation of clinical facts by observation, or the empirical method of developing medical knowledge which time has shown to be the only efficient method. Hippocrates displayed the noblest conception of the medical vocation, and in this, with his method of developing clinical knowledge, he set a standard and example for all time.
The doctrines of Hippocrates did not immediately gain general acceptance; soon after his death they nearly fell into oblivion, but six centuries later they were revived and given a vogue by Galen and then attained a dominant influence which they continued to exercise until the dawn of the modern era. During the interval between Hippocrates and Galen (B.C. 400 to 200 A.D.) a number of medical systems developed and continued in force for varying periods. The principal of these systems were:
1. The Dogmatic School.—This, based on the theories of Plato (B.C. 427-347), was developed by the immediate successors of Hippocrates, but it survived for only a few decades. The doctrines of this sect were highly speculative, and the humoral pathology was a fundamental tenet.
2. The school or following of Herophilus, originally located in Alexandria, flourished about B.C. 290 to A.D. 100. Herophilus, its founder, lived about 335-280 B.C., was one of the earliest anatomical investigators, and in part followed Hippocrates.
3. The school of Erasistratus, a famous contemporary and rival of Herophilus, also of Alexandria. His following flourished about B.C. 280 to A.D. 200.
4. The Empirical School, which existed about B.C. 280 to A.D. 117, was based on the skeptical philosophy of Pyrrho (B.C. 376-288). It rejected hypothetical speculations on the underlying causes and nature of phenomena, and recognized as valid only such knowledge as was derived from observation and experience. This school, therefore, had the only successful method of developing knowledge, identical with the modern inductive and scientific method, but it was not acceptable to the ancient and medieval habits of thought.