262 The Idea of Evolution. 



and the laws concerning a species or collection of individuals, 

 and even beyond that a similar resemblance in the laws which 

 governed associations or communities of species, such as, for 

 instance, a wood or marsh or grass meadow. In a wood you 

 found a number of different species living together in such a 

 way that while each individual had its own existence, yet its 

 existence was governed by the welfare of the whole wood. 

 Also in a species we found something of the same sort, and 

 again in cells of the body of a plant or animal. The existence 

 of each cell was independent in itself, but it was governed by 

 the act of the whole organisation. He thought, looking at things 

 in that manner, that one gradually perceived the definite scientific 

 reason for a great many points that were generally left outside 

 the field of scientific inquiry. We found in nature one form of 

 \egetation competing with another. The place where they were 

 now had been at one time probably covered by coniferous or 

 geological vegetation of some sort. After the retreat of the 

 ice that neighbourhood would be first of all covered by a very 

 scanty vegetation of alpine plants. Then would come probably 

 a pine forest covering the whole of the Nith valley, and much 

 later on the old Caledonian oak forest would cover the whole 

 of that neighbourhood. And then, last of all, but still in perfect 

 continuity with the preceding, they had that particular spot of 

 ground utilised by the one animal that was capable of the 

 reverent study of nature, and also of subduing nature for his own 

 purposes. We saw that the vegetation of the earth might be 

 explained and understood scientifically by the study of the first 

 few chapters of Genesis. He was rather afraid when he chose 

 that subject to address them upon that night that he might 

 possibly hurt the feelings of some of them in dealing with this 

 question of evolution from a wholly scientific spirit, but as they 

 saw he had put down the origin of these variations to a \'ast 

 quantity of minute and imperceptible changes in the environment, 

 or if they wanted one word for it they might say to chance. 

 They might ask — "What is chance?" There was no better 

 answer than the very old one — chance was a cause unperceived 

 bv human logic. 



