34 THE EVOLUTION OF SCIENCE. 



in the middle of the century, we rind that Robert Boyle 

 was experimenting and writing vigorously against the 

 empiricism of the Paracelsians, and turning all the en- 

 ergies of chemical research toward the discovery of the 

 elements — not of medicines, but of matter itself. The 

 search after truth had suprjlanted the search after the 

 philosopher's stone ; the love of truth for its own sake 

 took the place of the love of truth for the sake of physi- 

 cal health and ease ; and in less than half a century af- 

 terward, the dead mass of chemical knowledge — the ac- 

 cumulation of ages — was transformed into a living science. 



All history, modern as well as ancient, would be found 

 to confirm the conclusion that the love of truth for its 

 own sake is the principle of life in science. There was 

 no science of nature before this spirit entered the body 

 of human knowledge ; there will again be none if ever 

 this spirit shall take its flight. 



In addition to this element, there is another which 

 contributes especially to the growth of science. I refer 

 to the faculty of invention. Next to the love of truth, 

 which prompts investigation, that which contributes 

 most largely to its success is the power to invent hy- 

 potheses and the instrumental means to test their truth 

 by bringing them in direct contact with the facts of 

 nature. 



For example : next to the astronomer himself the most 

 vital agent for the growth of astronomy is his observa- 

 tory. Let us consider its equipment. There are tele- 

 scopes, small and gigantic, with curved glasses, true 

 to the fraction of a hair, mounted on masonry as firm 

 as the native rock, and driven by mechanism whose 

 motions are as equable as the rotation of the earth. 

 There are circles for the measurement of angles, with 

 graduations, accurate to the last degree of refinement, 

 with clocks and cronographs, which mark the passing 

 moments with a precision corresponding with the pre- 



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