THE LESSON OF EVOLUTION 3 



I am quite aware that the theme I have selected 

 is an ambitious one. But if our ideas are ever to 

 crystallise into some definite shape, it is necessary 

 that a general survey of the position should occasion- 

 ally be made ; and I do not know a better opportunity 

 than the Presidential Address to an Association like 

 this, where all branches of science are represented. I 

 do not claim to speak with authority ; nor do I wish 

 to pose as a philosopher. But I will give you a 

 simple statement of the conclusions to which I have 

 been led, and so, I hope, enable each of you to form 

 his own opinion of their value. 



THE GROWTH OF NATURAL PHILOSOPHY 



Ever since the dawn of the human intellect man has 

 tried to increase his knowledge in two ways by 

 observation and by speculation. Observation came 

 first, for that is common to man and animals. Specu- 

 lation is a distinctly human attribute, and we find 

 that it soon outdistanced observation and formed the 

 basis of the earlier philosophies. But during the last 

 few centuries the observational method has once more 

 come to the front under the name of science, and its 

 conclusions have not always been in accord with those 

 of the speculative philosophies which preceded it. 



The difference between the two methods is that 

 whereas speculation starts a chain of reasoning from 

 one or two propositions which are taken as absolutely 

 true, science reasons from the basis of as large a 

 number of observations as possible, and tries to find an 

 hypothesis which connects them all together, or ex- 

 plains them, as it is usually called. 



