348 The Study of Animal Life app. 



historians of science would in the main confirm this. But it is 

 also true that science reacts on the arts and sometimes improves 

 them. 



There may be peculiar aberrations of the art of medicine due to 

 the progress of the science thereof, but these are because the science 

 is partial, and hardly affect the general fact that scientific progress 

 has advanced the art of healing. The results of science have like- 

 wise supplied a basis to the endeavours to prevent disease and to 

 increase healthfulness, not only by definite hygienic practice but 

 perhaps still more by diffusing some precise knowledge of the 

 conditions of health. 



The generalisations of biology, realised in men's minds, must in 

 some measure affect practice and public opinion. Spencer's 

 induction that the rate of reproduction varies inversely with the 

 degree of development sheds a hopeful light on the population 

 question ; the recognition of the influence which function and sur- 

 roundings have upon the organism suggests criticism of many 

 modes of economic production ; a knowledge of the facts and 

 theory of heredity must have an increasing influence on the art of 

 eugenics. Nor can I believe that the theory of evolution which 

 men hold, granting that it is in part an expression of their life and 

 social environment, does not also react on these. 



In short, the direct application of biological knowledge ' in the 

 various arts of medicine, hygiene, physical education, and eugenics, 

 helps us to perfect our environment and our relations with it, helps 

 us to discover — if not the "elixir vitae" — some not despicable 

 substitute. And likewise, a realisation of the facts and principles of 

 biology helps us to criticise, justify, and regulate conduct, suggest- 

 ing how the art of life may be better learned, how human relations 

 may be more wisely harmonised, how we may guide and help the 

 ascent of man. 



8. Intellectual Justification of Biology.— But another 



partial justification of Biology is found in our desire to understand 

 things, in our dislike of obscurities, in our inborn curiosity. There 

 is an intellectual as well as a practical and ethical justification of 

 the study of organic life. 



Through our senses we become aware of the world of which we 

 form a part. We cannot know it in itself, for we are part of it and 

 only know it as it becomes part of us. We know only fractions of 

 reality — real at least to us — and these are unified in our experience. 



(i) In the world around us we are accustomed to distinguish 

 four orders of facts. ' ' Matter " and ' ' energy " we call those which 

 seem to us fundamental, because all that we know by our senses 

 are forms of these. The study of matter and energy — or perhaps 

 we may say the study of matter in motion — considered apart from 



