Herophilus who was born in Chalcedon, was a student of Praxagoras of Cos who in turn, was believed to be the first to tell the difference between arteries and veins. Prior to this the arteries was thought to carry air around the body, similar to their function in carrying oxygen enriched red cells around the body except even Praxagoras thought the air was delivered directly to the heart and brain via these vessels.
Herophilus was another who studied and practised his trade in Alexander at the time of Ptolemy. His initial suggestion that the arteries contained blood as opposed to air was widely disregard as even years before Aristotle believed that they contained air.
His biggest claim to fame was his dissection of cadavers (sometimes in public) to prove his theories. Together with Erasistratus he is regarded as a founder of the great medical school of Alexandria. .56
After the early Ptolemy period the philosophy that guided medicine was torn between different camps, you followed either Hippocrates methods Herophilus or Erasistratus methods, however a movement led by the physician Heraclides of Tarentum based all their knowledge on that gained through experience, spurning the use of dissection to gain anatomical knowledge.
The post Hippocratic schools of medicine, which were four in number:
These occupy perhaps a somewhat unimportant sphere in the history of medicine, but the great Philosophic schools of the Stoics, Epicureans, Sceptics, and Eclectics which influenced them, and of which, in a sense, they were the practical outcome, are famous through all time. No attempt will be named to describe them or try to explain their points of contact with medicine.
The school of the Dogmatists in its prime synchronized with
the decline of Hellenic freedom and with the rise of the
Macedonian hegemony. This school received its name from
Galen, and, though not very happily chosen, it must be
retained for convenience.
If we were to call them “theorists’" we should come nearer to the essential idea which they represented in the ancient world. 57
To the modern mind dogmatism is suggestive of a certain degree of intellectual rigidity and aridity which were certainly not characteristics of this ancient medical school. But they suffered from what Bacon called :
“that first distemper of learning, when men study words and not matter.”58