Introductory. 15 



operating immediately in numberless acts of special 

 creation, and the theory of natural causes as a whole, 

 whether these happen, or do not happen, to have been 

 hitherto discovered. 



This much by way of preliminaries being under- 

 stood, we have next to notice that whichever of the 

 two rival theories we choose to entertain, we are not 

 here concerned with any question touching the origin 

 of life. We are concerned only with the origin of 

 particular forms of life that is to say, with the origin 

 of species. The theory of descent starts from life as 

 a datttm already granted. How life itself came to be, 

 the theory of descent, as such, is not concerned to 

 show. Therefore, in the present discussion, I will take 

 the existence of life as a fact which does not fall 

 within the range of our present discussion. No doubt 

 the question as to the origin of life is in itself a deeply 

 interesting question, and although in the opinion of 

 most biologists it is a question which we may well 

 hope will some day fall within the range of science to 

 answer, at present, it must be confessed, science is not 

 in a position to furnish so much as any suggestion upon 

 the subject ; and therefore our wisdom as men of 

 science is frankly to acknowledge that such is the case. 



We are now in a position to observe that the theory 

 of organic evolution is strongly recommended to our 

 acceptance on merely antecedent grounds, by the fact 

 that it is in full accordance with what is known as the 

 principle of continuity. By the principle of continuity 

 is meant the uniformity of nature, in virtue of which 

 the many and varied processes going on in nature are 

 due to the same kind of method, i. e. the method of 



