2 THE PRESIDENTIAL ADDRESS 



as he was on that occasion. I can say in his presence that the lapse of 

 time has not failed to justify Lord Balfour's words. What was then 

 an intelligent anticipation is now an historical fact. 



I wish I could proceed on an equally cheerful note. The reputa- 

 tion of the scientific school in the Cavendish Laboratory has been 

 more than sustained in the interval under the leadership of one 

 whose friendly presence we all miss to-night. The death of Ernest 

 Rutherford leaves a blank which we can never hope to see entirely 

 filled in our day. We know that the whole scientific world joins 

 with us in mourning his loss. 



Lord Balfour's address was devoted to topics which had long 

 been of profound interest to him. He was one of the first to 

 compare the world picture drawn by science and the world picture 

 drawn by the crude application of the senses, and he emphasised 

 the contrast between them. A quotation from his address will 

 serve as an appropriate text to introduce the point of view which 

 I wish to develop this evening. 



' So far,' he said, ' as natural science can tell us, every quality 

 of sense or intellect which does not help us to fight, to eat, and to 

 bring up our children, is but a by-product of the qualities which do. 

 Our organs of sense perception were not given us for purposes of 

 research . . . either because too direct a vision of physical reality 

 was a hindrance, not a help in the struggle for existence ... or 

 because with so imperfect a material as living tissue no better result 

 could be attained.' 



Some of those who learn the results of modern science from a 

 standpoint of general or philosophical interest come away, I believe, 

 with the impression that what the senses tell us about the external 

 world is shown to be altogether misleading. They learn, for ex- 

 ample, that the apparent or space-filling quality of the objects called 

 solid or liquid is a delusion, and that the volume of space occupied 

 is held to be very small compared with that which remains vacant 

 in between. This is in such violent contrast with what direct 

 observation seems to show that they believe they are asked to give 

 up the general position that what we learn from our senses must be 

 our main guide in studying the nature of things. 



Now this is in complete contrast with the standpoint of the experi- 

 mental philosopher. He knows very well that in his work he does 

 and must trust in the last resort almost entirely to what can be seen, 

 and that his knowledge of the external world is based upon it : and 

 I do not think that even the metaphysician claims that we can learn 

 much in any other way. It is true that the conclusions of modern 

 science seem at first sight to be very far removed from what our 

 senses tell us. But on the whole the tendency of progress is to 

 bring the more remote conclusions within the province of direct 



