132 MR. DARWIN'S CRITICS v 



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 

 substantial 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, becomes its substantial form, and is the 

 source of all the powers and faculties of man of 

 all the vital and sensitive phenomena which he 

 exhibits just as the substantial 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 fit," though not true of the substantial form 

 of man, is true of the substantial forms of all 

 other bodies, the endless mutations 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 



