164 SECTIONAL ADDRESSES. 



The process of application of the exact sciences to physiology consists 

 in reality of studying the phenomena themselves and then adopting the 

 most plausible explanation capable of formulation in terms of the exact 

 science. There is no other way. But let us be under no illusion about 

 finding final explanations of what life is by this or any other methods. 



The enormously rapid developments of physics in recent years strike 

 the uninitiated onlooker dumb with an almost religious awe. Matter 

 and energy are as fleeting as time, and the ingenuity of man has spanned 

 the mighty extent of the known universe. Matter, energy, time and space 

 are in the melting-pot, and out of it will come we know not what of strange 

 relations of one to another. Of one thing we may be sure — that no final 

 explanation will follow. Lines of separation previously held to be rigid 

 will probably fade away, and there will be found to be a continuity between 

 matter and energy, between living and non-living, between the conscious 

 and the unconscious. But since philosophy cannot arrive at an explana- 

 tion of the nature of human understanding, the great mystery of the 

 origin, nature and purpose of life will, I think, always remain to tease, 

 stimulate or humiliate us. 



Each must decide for himself what view he takes, and as many of our 

 religious and philosophical beliefs are no doubt unconscious wish-fulfil- 

 ments, I feel that it ultimately amounts to our decisions being dependent 

 upon our individual temperaments, or, in other words, on our personal 

 physiological make-up. 



It was pointed out long ago by Claude Bernard that all a priori defini- 

 tions of life, like those of time, space or matter, are futile, since they 

 usually themselves imply the thing defined. Let us take one or two 

 famous definitions of life as examples. Bichat in 1818 defined life as 

 ' the sum total of those functions which resist death.' Here we have 

 two opposed ideas, life and death. ' All that lives will die ; all that is 

 dead has lived.' For Bichat life is a struggle of the living thing against 

 an environment which seeks to destroy it, but it is clear that the idea of 

 life as opposed to death is implicit in the defijiition. This idea of an 

 internal teleological principle, of entelechy, runs through all biological 

 writings back to Aristotle, with whom we believe it to have originated. 

 The amoeba which encysts itself does so in order to defy adverse conditions 

 in its environment. The ' calculating intelligence ' postulated by Kant 

 directs this response. 



Another definition of life which has been much favoured of late is the 

 mechanistic one in various forms ; ' life is a special activity of organised 

 things.' Here again the definition implies the idea itself. The possession 

 and maintenance of a definite structure cannot any longer be held to be 

 an outstanding feature of living matter as commonly understood, for 

 recent researches in physics show us that, although electrons may come 

 and go, the atomic structure of matter is relatively stable, even though 

 under particular circumstances mutations may occur. Nevertheless the 

 view of life as a mechanism created by and entirely dependent upon its 

 environment gained strength owing to the developments in other sciences, 

 particularly by reason of the synthesis of organic compounds, the principle 

 of the conservation of energy and the introduction of the Darwinian theory 

 of evolution. According to this view, a revival of that of Empedocles, 



