An Introduction to a Biology 



theories, or for a theory he himself has put forward. Now, 

 although I have just described the method of investigation 

 of nature as consisting -first of description and then of inter- 

 pretation, it is only in quite recent years that the necessity 

 for this chronological sequence has been recognised. The 

 merest glance at the history of human thought suffices to 

 show that the farther we go back in time the more does the 

 proper order of description and interpretation tend to be 

 reversed. We need go no farther back than the Middle 

 Ages for an example of a time when a complete interpretation 

 of the universe was not only attempted but believed in so 

 firmly by men that they killed those who denied it. Yet 

 not the smallest fraction of that universe had been trust- 

 worthily described. 



To-day we profess greater modesty as to the complete- 

 ness of our interpretation. Yet those of us whose knowledge 

 of nature is culled from textbooks written by people who 

 talk about natural processes being governed by immutable 

 laws, have got no further than handing over the government 

 of the universe from a hierarchy of spirits and demons to 

 one of principles and laws. Even those men of science who 

 see that this notion is nonsense make the most unwarrantable 

 assumptions. We are told that living nature is orderly and 

 not chaotic ; that the more we find out about it the more 

 simple will it become and the less complicated ; that if a 

 fundamental principle is discovered in the case of animals, 

 it will be true also of plants ; and so forth. These things 

 may be so. But it is our business not to assume that they 

 are, but to find out if they are. And we are far from knowing 

 that yet. 



As it with our general view of nature, so it is with our 

 investigation of particular problems. At the threshold of 

 a piece of research, Interpretation does not politely wait at 

 the door and say, " Allow me ; Description first," but both 

 rush in together without ceremony, hand in hand ; with the 

 result that the work of Description is always influenced by 



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