THE MEANING OF ' NATURE ' 259 



we become aware of a special divergence in the use of the word 

 nature throughout the philosophy of nature. 



In his explanation of this word, St. Thomas says: " Nature 

 is the principle of the movements of composite things, but not 

 primarily. Thus the fact that an animal moves downwards 

 [i.e., falls] does not proceed from the nature of the animal as 

 animal but from the nature of the dominating element.""^ 

 Nature, then, is a principle primarily of those movements that 

 belong to things in virtue of what is most fundamental in 

 them.-' 



Nor is this the only instance in which St. Thomas adverts 

 to this idea. When, for example, Aristotle speaks of generation 

 as the activity the most natural of all living things, St. Thomas 

 explains that it is a movement common to all mobile beings, 

 even to the inanimate. ^*^ Again, St. Thomas, speaking of the 

 vegetative soul, reserves the term nature for what living and 

 non-living things have in common: " Now this principle is not 

 nature. Nature does not move in opposite directions, for all 

 plants grow not only upwards or downwards, but in both direc- 

 tions." ■' It seems, then, that in these passages the soul is taken 

 to be nature only insofar as it is the principle of movements 

 common to all mobile beings — though in other places of the 

 De Anima it is clear that the soul as such is regarded as 

 nature.^^ 



What is most common, of course, is also what is most funda- 

 mental in any mobile being; and this, we are saying, is what is 



" In II Phys., lect. 1, n. 5. 



^* John of St. Thomas takes the word jmmarily to mean that the nature of a 

 being is not a secondary and instrumental principle, such as an accident would be, 

 but a fundamental principle, i. e., substantial. That nature must be primary in 

 this sense is readily evident. St. Thomas, however, seems to see another meaning 

 in the word jmTnarily. 



^* Aristotle, De Anima, II, 4, 415a22 et sqq.; St. Thomas, In II De Anima, 

 lect. 7, n. 312. 



" St. Thomas, In II De Anima, lect. 3, n. 257. 



^^ Cf. Aristotle, De Anima, I, 1; St. Thomas, lect. 2, where it is established 

 that the study of the soul belongs to philosophy of nature insofar as the proper 

 activities of the soul involve modifications of the body. Also, Aristotle, De Anima, 

 Bk. II, 4, 415 b 22 et sqq. where the soul is seen as a principle of movement. 



