MEDICINE AND PHILOSOPHY IITH AND 12TH CENTURIES 107 



to one of the cells resulted in the loss of the function associated 

 with it without affecting the other functions.^^ Sensation is a 

 function of the body which man shares with other animals; 

 distinguishing and understanding are functions of the soul, 

 peculiar to man. There are three powers of the soul: under- 

 standing {intelligentia) by which man perceives incorporeal 

 things with the certain reason why they are thus; reason by 

 which man perceives in what respects things agree with other 

 things and in what they differ; memory by which man firmly 

 retains what was known before. 



The doctrine of elements provided William of Conches with 

 more than the simple parts from which to construct things, 

 organisms, and a universe; they were also principles for the 

 examination of the relation of corporeal things perceived in 

 sense experience to the incorporeal structures conceived by the 

 mind and used to explain the nature of corporeal things. The 

 processes of composition and resolution which related elements 

 as qualitatively and quantitatively simple parts to composite 

 wholes also crossed the line which separates seen from unseen 

 and corporeal from incorporeal. William's analyses therefore 

 have philosophic interest (since he explores the problems 

 involved in these relations) and empirical content (since the 

 structures w^hich he abstracts are found embodied in things 

 which are and are known) . The elements serve similar func- 

 tions in other twelfth century cosmologies, scientific treatises, 

 and encyclopaedias, and they provide common principles for 

 the work of William of Conches and the work of men like 

 Thierry of Chartres and Peter Abailard who influenced him and 

 of William of St. Thierry who criticized him. 



Thierry of Chartres was Chancellor of the School of Chartres 

 from about 1141 to about 1150. John of Salisbury calls him 

 " the most zealous investigator of the arts," and another disciple 

 says he was " preeminent among the philosophers of all Europe " 

 {totius Europae philosophorum precipuus) . Bernard Sylvestris 

 dedicated the De Universitate Mundi to him, and two of his 



" Ibid., IV, 24, PL 172, 95. 



