154 SCIENCE AND THE HUMAN MIND 



ledge, till, in the Darwinian theory of natural selec- 

 tion, its less clear-sighted advocates saw a complete 

 account of life and its phenomena. In a future 

 chapter we shall trace the widening of this sharply- 

 cut but somewhat dry and meagre philosophy into a 

 broader and fuller idea of the complexity and wonder 

 of the Universe. But, throughout the greater part of 

 the nineteenth century, the true method of advance 

 lay in building up this naturalistic edifice in new and 

 extending directions, and in proving its capacity to 

 interpret phenomena, of which some were thought 

 inexplicable and others were then unknown. 



For the work of the Renaissance and the succeeding 

 ages had been to bring within the circle of the com- 

 prehension of man phenomena with which he had 

 long been acquainted, and most of which were easily 

 apparent to his unaided senses. But now we pass 

 to a time when scientific work consisted largely 

 in revealing the hitherto unknown and hitherto 

 unknowable as well as in explaining them when re- 

 vealed. An extension of the senses had been produced 

 by the perfectioning of such instruments as micro- 

 scopes and telescopes, and their adaptation to photo- 

 graphy. Hence followed the discovery of living cells 

 as the units of the organism, and of the structure of 

 far-distant stars and suns. Then the disclosure of 

 all the vast and complex phenomena of electricity, 

 to name but the most striking instance out of many, 

 opened up fresh worlds for science to conquer, worlds 

 which proved amenable to the same logical methods 

 of investigation that were first tested in dynamics 

 and astronomy. 



When the nineteenth century opened, the great 



