18 CHAPTERS ON EVOLUTION. 



beliefs, however time-honoured they may be, by the newer phases of 

 thought to which his studies have led. 



Four very definite questions may be said to contain in their 

 replies, the materials for constructing the full history of any living 

 being. The queries to which I allude are such as the child might 

 well ask respecting any object presented for the first time to his view; 

 and it is worthy of note that the methods of inquiry through which 

 the cumulative experience of ordinary life is gained find in the ques- 

 tionings of science a striking parallel. First, and most naturally, we 

 inquire concerning the living being, " What is it ? " Next in order 

 comes the question, " How does it live ? " Thirdly, the query, 

 " Where is it found ? " appears as a most natural inquiry ; and 

 the question, " How has it come to be what it is ? " may fitly 

 close the list of scientific interrogations. It may be said that, 

 could we perfectly and fully answer these four queries as applied 

 to any living thing, the history of such a form might be regarded 

 as being in every sense complete. Its present history, its past 

 existence, its way of life, its bodily mechanism, its evolution and 

 descent these, and other points in which the life and being of an 

 animal or plant is summed up, are included in the replies to our four 

 queries. Answer these questions fully, I repeat, respecting an animal 

 or plant, and you leave no item in its history unexplained. When 

 they shall have been fully answered respecting the known organic 

 world, then will dawn a millennium in biological and other sciences, 

 of which, however, not the remotest shadow of a dream has yet 

 crossed the scientific expectation. Full as our knowledge is on 

 many points of structure and life history, biologists too frankly 

 recognise the gaps in their information to hope for or expect the 

 completion of their science even in the most distant years that from 

 the present horizon we care to scan. Still, the labour of investigation 

 proceeds apace slowly, it may be, yet hopefully ; and every scientific 

 advance which the present sees or the future may know, may assuredly 

 be regarded as filling up, wholly or in part, one or more of the replies 

 to the four questions wherein, as we have seen, the gist of biology is 

 comprised. 



The principle of the division of labour which has wrought such 

 wonderful changes and improvements in human affairs, political, 

 social, and commercial, has extended its advantages to the domain 

 of life-science, in that each query possesses its allotted branch as 

 the agent for supplying its answer. Part of the excellence of bio- 

 logical reasoning, and of scientific method at large, consists in the fact 

 that the labour of investigation is divided amongst three well-marked 

 branches of inquiry j whilst the answers to the fourth and last ques- 

 tion on our list are in reality supplied by the concentrated knowledge 

 of the three preceding replies. Thus, to the question "What is it ?" 



