260 SHEILAH o'fLYNN BRENNAN 



most natural. "'^ This fact is significant especially in the case of 

 living beings where one can distinguish between various types 

 of movements, some more fundamental than others. We could 

 say that movements such as being generated (in a broad sense) 

 and falling would be more natural than growing, and growing 

 more natural than sensing, and sensing more natural than 

 understanding (which is not natural at all in the strict sense 

 given to natural in the philosophy of nature) . 



Now why is it that what is most common and most funda- 

 mental is also the most natural.? We have said that nature is 

 a principle of movement in that in which it is. It is therefore 

 a principle of movement in the mobile — in the moving or move- 

 able thing. A mobile thing implies potency and passivity. It 

 does not necessarily involve activity; this is the mark of the 

 mover. Nature then is intimately related to matter. Though 

 form is nature more perfectly than matter is, since matter 

 would not be a principle of movement without its relation to 

 form, and no being would be a natural being in act were it 

 not for form; nevertheless, form is nature only insofar as it 

 determines matter, because otherwise it would not be a princi- 

 ple of movement at all. Where there is no matter, there is no 

 nature. And in the measure that form rises above matter it 

 reaches beyond mere nature, as it becomes, first, a principle not 

 only of being moved but also of moving, and then a principle 

 not only of movement but of operations that are not strictly 

 movements at all. 



Let us look more closely at this gradation in natural beings. 

 One step above the bottom, we have the plants, differentiated 

 from inanimate things by the vegetative soul. Now, this soul, 

 like any other, even the human soul, is most fundamentally 



^* It must be noted that we are taking nature and natural absolutely. Thus, 

 absolutely considered, sensing is less natural than growing though relative to the 

 animal it is more natural, since it is proper to the animal nature and growing is 

 not. Likewise, understanding and willing are more natural for man than sensing, 

 though in an absolute sense they are what is least natural in him, if they are 

 natural at all, and what is most natural of all is anything he has in common with 

 the lowest thing in nature. 



