NEW CONCEPTIONS IN SCIENCE 



may be called a logical imagination. I will offer 

 an illustration: 



Sir Isaac Newton was not merely the most power- 

 ful genius of his time, but, as many references in 

 the foregoing pages have disclosed, the range of his 

 inquiries and his speculations was extraordinary. 

 His stock of information must have wellnigh ex- 

 hausted the possibilities of his day. Yet could he 

 return now, when scarce a century and a half have 

 gone by, he would own himself a most puzzled and 

 ignorant man. 



Newton laid the foundations of the science of 

 light, yet of the nature of light that it is simply a 

 form of electricity he had no mortal idea. He 

 had no idea of the action of light on certain me- 

 tallic salts, so if he were shown a photograph of 

 Lord Kelvin, for example, he would have no notion 

 of how it was made. He seems to have been the 

 first to study the effect of a glass prism upon a beam 

 of light ; he was practically the inventor of the spec- 

 troscope. Yet he would probably have regarded a 

 man as clean daft who would have told him that 

 this simple device would one day tell us what the 

 sun is made of, and measure the speed of the most 

 distant stars; would reveal to us new kinds of 

 matter, new substances of whose existence no one 

 had dreamed before, and perhaps give us a clew to 

 the origin of worlds. Were he shown Professor 



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