x.] MR. DARWIN'S CRITICS. 227 



form of the water is not only the cause (radix) of the 

 coolness of the water, but also of its moisture, of its 

 density, and of all its other properties. 



It will thus be seen that "substantial forms " play nearly 

 the same part in the scholastic philosophy as " forces " 

 do in modern science ; the general tendency of modern 

 thought being to conceive all bodies as resolvable into 

 material particles and forces, in virtue of which last 

 these particles assume those dispositions and exercise 

 those powers which are characteristic of each particular 

 kind of matter. 



But the Schoolmen distinguished two kinds of sub- 

 stantial forms, the one spiritual and the other material. 

 The former division is represented by the human soul, 

 the anima rationalis ; and they affirm as a matter, not 

 merely of reason, but of faith, that every human soul 

 is created out of nothing, and by this act of creation 

 is endowed with the power of existing for all eternity, 

 apart from the materia prima of which the corporeal 

 frame of man is composed. And the anima rationalis, 

 once united with the materia prima of the body, be- 

 comes its substantial form, and is the source of all the 

 powers and faculties of man of all the vital and sen- 

 sitive phenomena which he exhibits just as the sub- 

 stantial form of water is the source of all its qualities. 



The " material substantial forms " are those which 

 inform all other natural bodies except that of man ; and 

 the object of Suarez in the present Disputation, is to 

 show that the axiom " ex nihilo nihil Jit" though not 

 true of the substantial form of man, is true of the 

 substantial forms of all other bodies, the endless muta- 

 tions of which constitute the ordinary course of nature. 

 The origin of the difficulty which he discusses is easily 

 comprehensible. Suppose a piece of bright iron to be 

 exposed to the air. The existence of the iron depends 



