SCIENTIFIC METHOD 27 



expected that a few apt sentences should describe defi- 

 nitely the processes by which man achieves his destiny 

 and slowly rises to a knowledge of his surroundings ? At 

 the risk, however, of being thought dogmatic, I venture 

 to state, in one sentence, what, as a follower of Bacon, I 

 believe to be the essence of my subject; the sentence 

 which appeals to me as descriptive is, however, not 

 Bacon's but Virgil's : 



Felix qui potuit rerum cognoscere causas 1 . 

 In this well-known and felicitous line I seem to grasp the 

 core of my subject, for this describes the scientific spirit, 

 happy only in so far as it strives to know the causes of 

 things. The scientific method comprises all those modes 

 of mental activity which are best adapted to attain this 

 end. It is not a hard-and-fast system of thought ; it is 

 not a particular method of observation or of experiment ; 

 it is not any special technique. In itself, the method is 

 meaningless ; it acquires merit through its aim, and is 

 significant because of its purpose. Its form may, and 

 indeed must, be plastic, varying with the condition of 

 man and of nature, but its end remains throughout the 

 same the revelation of the truth about things. Man is 

 so constituted that he must strive to understand himself ; 

 his experience has to be made more intelligible to him ; 

 in natural science this intelligibility is bound up with the 

 causation of those natural phenomena which surround 

 him from the cradle to the grave. I use the term 

 'causation' here in the sense so definitely indicated by 

 Mill, ' a cause which is itself a phenomenon without 

 reference to the ultimate cause of anything,' what, in 

 short, is spoken of in metaphysics as the ' physical ', not 

 the ' efficient' cause ; the term is thus employed ' in that 



1 Virgil, Georgics, ii. 490. 



