Erasistratus, who was born on the Greek island of Chios, came from a distinctly medical background and studied in Athens, Cos, and Alexandria. Following Herophilus he became the leading figure in the Alexandrian School of Anatomy.

It is possible with Erasistratus, unlike his contemporaries, to make out at least the outline of his physiological system. Every organ and part of the body was served by a ‘three-fold network’ of vein, artery, and nerve. Indeed he believed the body tissues were a plaiting of such vessels, which at their extremities became so fine as to be invisible. The veins carried blood and the nerves and arteries transported nervous and animal spirits respectively.

As an atomist he rejected all attractive and occult forces seeking instead to explain everything in terms of atoms and the void. He thus accounted for the bleeding of severed arteries by assuming the escaped pneuma left a vacuum that was filled by blood from adjoining veins.

One of the most interesting aspects of his thought was his unusual rejection of the humoral theory of disease which, formulated by the Hippocratics and authorized by Galen became the sterile orthodoxy of Western medicine for 2000 years. Instead he seems to have argued for a more mechanical concept of disease, attributing it to a ‘plethora’ of blood, vital spirit, or food, which produces a blocking and inflammation of the various vessels.

His objection to the humoral theory found little support and with the passing of Erasistratus the great innovative period of Alexandrian medicine came to an end.