THE MEANING OF NATURE' 249 



precisions: nature is the primary matter, whether this latter 

 be absolutely first or first only in a certain order; ^ and nature 

 is the form or essence as well, which is the end of generation. - 



6. By " an extension of meaning," finally, any essence 



{ovcria) is called nature, whether it be the term of generation 



or not, because a nature is one kind of essence. It is in this 



sense that we can speak of the nature of a circle or of an 



immaterial substance.^ 



In conclusion, Aristotle makes the point that it is the form 

 that is primarily and most properly nature, for the matter is 

 called nature insofar as it is receptive of the form, and genera- 

 tion and growth are called nature because they are movements 

 proceeding from it: * " And nature, in this sense, is the source 

 of movement in natural things, which is in them in some way, 

 either potentially or actually." 



^ The examples given by Aristotle are in keeping with the views of certain of 

 his predecessors. Thus, for primary matter he gives not his own absolutely 

 prime matter, but something composite, one or several of the elements; and for the 

 form he gives — quoting Empedocles — not the substantial form, but the primary 

 composition of a thing. His purpose obviously was to show that the word nature 

 was in fact being used for primary matter and for form whatever these might be 

 understood to be. 



' Form, therefore, is a principle of a natural thing as a formal cause and a 

 principle of generation as a final cause. 



* It might be noted in addition that form or essence may be called nature, not 

 only as an end of generation, but as a source of accidental physical movement or 

 change, and that this meaning may be extended to include form or essence as 

 principle of movement in a more common sense, including any operation, even 

 spiritual. This would give us a more proper sense in which we could speak of the 

 nature of an immaterial substance, one closer to the original signification than 

 essence taken simply. In his De Ente et Essentia, St. Thomas gives this extended 

 sense as one of the meanings of nature (" a thing's essence as ordered to its proper 

 activity ") and even indicates that this seems to be what Aristotle means by 

 nature in Metaphysics V, where he says that in a certain sense every substance is 

 a nature (cf . no. 6, above) . 



* The form of the thing to be generated is a principle of generation as the end, 

 whereas the form of the progenitor is the active principle from which the generation 

 proceeds, the progenitor being the agent. Generation, of course, implies change 

 within the progenitor, the latter being a moved mover. As principle of this change, 

 the form is obviously a source of change in that in which it is and as such can 

 be taken to be nature. Just how the form of an agent, an active principle moving 

 another as such, may nevertheless be termed nature, a principle of change within 

 the changing being, will be discussed in the last footnote of this article. 



