326 POPULAR SCIENCE MONTHLY. 



In a later section of the book, in which he recurs to the subject, the 

 mocking tone of Diderot's professed submission to the 'teachings of 

 the faith,' only makes the more manifest the real opinion that he holds 

 and desires to get accepted. ' ' May it not be that, just as an individual 

 organism in the animal or vegetable kingdom comes into being, grows, 

 reaches maturity, perishes and disappears from view, so whole species 

 may pass through similar stages? If the faith had not taught us that 

 the animals came from the hands of the Creator just such as they are 

 now, and if it were permissible to have the least uncertainty about 

 their beginning and their end, might not the philosopher, left to his 

 own conjectures, suspect that the animal world (I'animalite) has from 

 eternity had its separate elements confusedly scattered through the 

 mass of matter; that it finally came about that these elements united 

 — simply because it was possible for them to unite; that the embryo 

 thus formed has passed through an infinite number of successive 

 organizations and developments; that it has acquired in turn move- 

 ment, sensation, ideas, thought, reflection, conscience, sentiments, pas- 

 sions, — signs, gestures, sounds, articulate speech, language — laws, sci- 

 ences and arts; that millions of years have elapsed between each of 

 these developments; that there are perhaps still new developments to 

 take place which are as yet unknown to us ; that there has been or is to 

 be a stationary condition of things; that the being thus developed is 

 passing out of, or will pass out of, that condition by a continual process 

 of decline, in which his faculties will gradually leave him just as they 

 originally came to him ; and that he will finally disappear from nature 

 forever, or rather, will continue to exist, but in a form and with 

 faculties wholly unlike those which characterize him in this moment 

 of time? — But religion spares us many wanderings and much labor." 

 Here, of course, we have not only the transformation of species, but 

 also the sketch of a complete system of materialistic and ateleological 

 evolutional philosophy, after the Spencerian fashion. Most of the 

 chapters of Mr. Spencer's elaborate biography of the universe Diderot 

 gives us in outline: — its 'integration of a diffused, incoherent matter,' 

 its 'successive phases of physical, psychical and social development,' 

 its 'equilibration' and resultant 'stationary state,' and finally its 

 'alternate cycles of evolution and dissolution.' 



The passage first quoted, however, seems to me the more interesting 

 of the two, not only because it is more outspoken and free from the 

 veil of ironical piety, but also because it shows clearly the sources 

 and grounds of Diderot's belief in the mutability of species. He had 

 been stimulated to write largely by the recent appearance of the 

 'Systeme da la Nature' of Maupertuis; but he ignored the embryo- 

 logical line of argument, and rested his conclusion upon the homologies 

 lately made known by Daubenton and dilated upon by Buffon. 



