THE MEANING OF NATURE ^55 



for form. We may consider prime matter in general as having 

 an appetite for form in general, or as the matter in a particular 

 substance (e. g., an acorn) having an inclination to a deter- 

 minate form (namely, the form of an oak tree) — the determin- 

 ation of the appetite being due, of course, to the form possessed 

 (i.e., the form of the acorn) . But the passive material principle 

 also includes secondary and accidental principles of receptivity 

 as in the case of water, which becomes warm when exposed to 

 fire. Such an accidental passive principle, of course, even 

 though material (i.e., receptive) , springs as a characteristic 

 fundamentally from the substantial form just as does the active 

 (or, if you prefer, passive) formal principle of being drawn 

 downwards for the stone. 



However, a new difficulty now arises, for to say that nature 

 may be merely a passive potency seems to do away with the 

 distinction between nature and art. Nature differs from art in 

 that nature is an intrinsic, art an extrinsic principle. But if this 

 intrinsic principle that is nature may be no more than a passive 

 potency, which of course is also required by art, the active 

 principle being, like art, extrinsic, where would the difference 

 lie.? St. Thomas saw this difficulty, as is evident in his com- 

 mentary on Book II of the Physics,^^ where he makes the 

 precision that in the case of nature this potency must be a 

 natural potency. In Book VIII, ch. 4, of the Physics Aristotle 

 distinguishes a violent movement from a natural one by the 

 fact that the latter is one to which the thing was in potency. 

 St. Thomas comments: " These things are naturally moved, 

 when they are moved to their proper acts, to which they are in 

 potency according to their nature." ^^ " To their proper acts " 

 implies that these things are not in potency to just any acts 

 or even to many acts, but to certain determinate acts fixed by 

 their nature (i. e., by their form, primarily) — to certain per- 

 fections wherein they find their fulfillment. Implied here is an 

 order of appetite intrinsic to the things. The passive potency 

 in the case of nature, then, involves a determinate inclination, 



^^ Lectio 1, n. 4. " /ra IX Phys., lect. 8, n. 1. 



