CLASSICAL ANTIQUITY, MIDDLE AGES 5I 

 of things is really possible; man can know nothing and prove nothing, not 

 even the impossibility of knowledge or justification for doubt. Such a funda- 

 mental principle naturally precluded any theoretical conception of nature, 

 whether Democritean or Aristotelean, but it was just this very circumstance 

 which drove a philosopher seeking after knowledge to become all the more 

 deeply engrossed in specialized science and its practical application. It was 

 thus exclusively through detailed anatomical research that the Alexandrian 

 medical school advanced the science of biology. 



Herophilus was a native of Chalcedon in Asia Minor, studied in the 

 Asclepiad schools in Cos and Cnidus, and afterwards worked as a teacher and 

 researcher in Alexandria. The dates of his birth and death are unknown, but 

 his activities fall within the decades about the year 300 b.c. His writings, 

 too, are lost, except for a few fragments; their contents are known to us only 

 through the references of other authors. That Herophilus was one of the 

 most prominent anatomists of antiquity is, however, universally acknowl- 

 edged, both by classical and by modern authors. His fame is based on the 

 numerous discoveries he made, particularly in human anatomy. Every part 

 of the human body was investigated by him, and what more than anything 

 else attracted the attention of his contemporaries was the fact that he em- 

 ployed human bodies for the purposes of investigation. Sceptics as they were, 

 he and his pupils despised the traditional fear of dissecting human bodies, 

 and the enlightened Ptolemaic rulers placed material at their disposal. It is 

 even declared that Herophilus took advantage of opportunities offered to 

 him to carry out investigations on living human beings — criminals con- 

 demned to death, whose internal organs he studied in a living state. ^ Among 

 the organs which he described in detail may specially be mentioned the brain; 

 he discovered and gave an account of its membranes and its venous blood 

 sinuses, which still bear his name, the torcular Herophili. Moreover, he 

 studied the ventricles of the brain, being particularly interested in the 

 fourth, which he regarded as the organ of the soul. He gave similar close 

 study to the eye, its membranes, film, and retina. He also described the ali- 

 mentary canal; the name "doudenum" for its upper section comes from him. 

 The liver he carefully studied with regard to the variations in its shape in 

 different individuals. The circulatory system he also made the subject of close 

 investigation; he compared the walls of the arteries and the veins and studied 

 the pulse at different ages and under different bodily conditions. That the 

 arteries contained the pneuma he believed in common with all other re- 

 searchers of his time. For the first time he cleared up the question of the dif- 

 ference between nerves and tendons. Finally, he carefully worked out the 



' One of the early Fathers, Tertullian, quotes, among other heinous acts committed by 

 the heathen, that Herophilus tortured to death six hundred persons — a story on a par with 

 much that is related nowadays in anti-vivisectionist literature. 



