256 SHEILAH o'flynn brennan 



an appetite, not to be found in the passive potency of art. Al- 

 though the potency in the case of the matter of artificial things 

 is limited to certain forms (e. g., wood cannot be used in the 

 making of any and all artifacts) , nevertheless there is no 

 positive inclination to any form. There is simply a non-repug- 

 nance. The determination that there is in art must come from 

 the extrinsic active principle, from the mind of the artist. The 

 potency itself, in the case of art, is a passive potency only 

 insofar as there is no repugnance to an act that man wishes to 

 impose upon it; it is a potency then only in relation to the 

 human mind, a sort of " obediential potency." The natural 

 potency, on the other hand, is intrinsically related to an act — 

 the act also being considered natural, even though in certain 

 cases it can be supplied only by a non-natural agent. 



It was by an application of this principle that St. Thomas 

 showed the movement of the heavenly bodies to be natural.^^ 

 For although they were moved by forces extrinsic to nature, 

 the separated intelligences, nevertheless from the point of view 

 of the passive potency, implying a determinate inclination or 

 aptitude to circular movement, the movement was said to be 

 natural. Another application may be seen in the case of evo- 

 lution. Though the active principle must certainly have been 

 outside of nature, the whole process would have been natural 

 from the standpoint of the passive inclination of matter, always 

 " desiring " as an end the more perfect fulfillment of its potency. 

 The act conferred was natural, corresponding to a natural 

 potency, though the power that conferred it was not.^^ 



It should be noted, moreover, that although the natural 

 potency in a thing implies an intrinsic order to an act, giving 

 rise to a relation between an appetite and a good, this good 

 need not be considered as a perfection of the thing in its own 

 particular being. Indeed, in the case of non-living things, it 



'•"Cf. St. Thomas, Contra Gentiles, HI, 23. 



** It might be asked if the active principle in such cases would be an example 

 of art cooperating with nature. It seems that it would not be — at least not in the 

 strict sense. Art, it seems, cooperates with nature when it acts in conjunction with 

 au active principle operating in nature, as is the case with medicine. 



