MEDICINE AND PHILOSOPHY IITH AND 12TH CENTURIES 109 



stages of creation. Among the elements, fire is an active and 

 efficient cause, earth a passive and material cause, while air 

 and water are both active and passive, instruments and vehicles 

 of causation. Among the seminal causes which determine pro- 

 cesses and developments after the formation of the world are 

 gravity and lightness which bring the elements into inter- 

 relations in local motion.^* 



Thierry proceeds from the creation of the world to an exposi- 

 tion according to the analysis of physicists (secunduvi rationem 

 physicoruTn) of the motions of heaven and earth as determined 

 by the properties and relations of elements. He argues that 

 when Moses said that the earth was without form and void, 

 and when he used other similar expressions, he was referring 

 to the " informity," or rather the " uniformity," of the four 

 elements. This " confusion " of elements, which the ancient 

 philosophers called matter (hyle) or chaos, is what Moses 

 signified by " heaven and earth." 



The informity of those elements then consisted in the fact that 

 each of them was almost of the same sort as the others and that the 

 differences between them were minimum or almost nothing. There- 

 fore that difference was held by the philosophers to be nothing, and 

 they called the elements thus confused one unformed matter. Plato, 

 however, considering the minimum which separates the elements, 

 and knowing that the difference, although minimum, is present in 

 the confusion, concluded consequently that matter, that is, the con- 

 fusion of elements, underlies the four elements themselves, not in 

 the sense that that confusion preceded the four elements in time 

 or creation, but in the sense that confusion naturally precedes 

 differentiation, as sound precedes word, or genus precedes species.^^ 



When Moses went on to say that the spirit of the Lord moved 

 upon the waters (Gen. 1: 2) , he distinguished the operative 

 cause from the material cause. The power of the artificer, 

 whom he calls the spirit of the Lord, excels and dominates 



'^^ Thierry of Chartres, De Sex Dierum Operibus, ed. M. Haureau, in Notices et 

 Extraits des Manuscrits de la Bibliotheque Rationale, Paris, 1888, vol. XXII, Part 2, 

 pp. 172-7. 



" Ihid., p. 179. 



