INTRODUCTION 



THE normal human being, shortly after he begins to 

 walk and talk, is brought by his walking into contact 

 with new objects and new happenings which arouse 

 his curiosity. And he uses his talking to ask, " What is that? " 

 For a time this potential intellect is satisfied with the names 

 of objects. In the course of time, unless he is repressed or 

 diverted, he will ask the more searching question, " How 

 come? " In regard to the vast array of plants and animals 

 that will come to his attention, two classes of answers have 

 been offered, yea three. To dismiss the last one first, as un- 

 worthy of serious consideration, we are reminded that for 

 some people a satisfactory answer to the question as to the 

 origin of the many living things is to say that they have 

 always been as they are now. The other answers are. First, 

 things were specially created. There are two different vari- 

 ants of this answer: (a) Each species or kind of living thing 

 was created by itself and has remained from the beginning 

 as we find it today; (b) The world was created in such a 

 way that the different living beings automatically came out 

 of the mechanism. This latter is substantially the explana- 

 tion of creation offered by Saint Augustine. Second, plants 

 and animals evolved from simpler to more complex forms in 

 accordance with the uniform action of natural forces, such 

 as are constantly at work in the world. 



The conception of a continuous process of change, in 

 the course of which the whole world and all of its inhabitants 

 come to be progressively different, appears very early in hu- 

 man thought. Long before Aristotle, becoming was clearly 

 differentiated by philosophers from being. The fact that 

 aspects of nature are constantly changing is perhaps accepted 

 by casual observers as a purely short-time phenomenon. The 



