USE OF T11K IMAGINATION. 419 



to take you beyond the boundary of mere observation, 

 into a region where things are intellectually discerned, 

 and to show you there the hidden mechanism of optical 

 action. 



But how are those hidden things to be revealed? Philos- 

 ophers may be right in affirming that we cannot transcend 

 experience: we can, at all events, carry it a long way from 

 its origin. We can magnify, diminish, qualify, and com- 

 bine experiences, so as to render them fit for purposes 

 entirely new. In explaining sensible phenomena, we 

 habitually form mental images of the ultra-sensible. There 

 are Tories even in science who regard Imagination as a 

 faculty to be feared and avoided rather than employed. 

 They have observed its action in weak vessels, and are un- 

 duly impressed by its disasters. But they might with 

 equal justice point to exploded boilers as an argument 

 against the use of steam. With accurate experiment and 

 observation to work upon, Imagination becomes the archi- 

 tect of physical theory. Newton's passage from a falling 

 apple to a falling moon was an act of the prepared imagi- 

 nation, without which the " laws of Kepler" could never 

 have been traced to their foundations. Out of the facts of 

 chemistry the constructive imagination of Dal ton formed 

 the atomic theory. Davy was richly endowed with the 

 imaginative faculty, while with Faraday its exercise was 

 incessant, preceding, accompanying and guiding all his 

 experiments. His strength and fertility as a discoverer is 

 to be referred in great part to the stimulus of his imagina- 

 tion. Scientific men fight shy of the word because of its 

 ultra-scientific connotations; but the fact is that without 

 the exercise of this power, our knowledge of nature would 

 be a mere tabulation of co-existences and sequences. We 

 should still believe in the succession of day and night, of 

 summer and winter; but the conception of Force would 

 vanish from our universe; causal relations would disappear, 

 and with them that science which is now binding the parts 

 of nature to an organic whole. 



I should like to illustrate by a few simple instances the 

 use that scientific men have already made of this power of 

 imagination, and to indicate afterward some of the further 

 uses that they are likely to make of it. Let us begin with 

 the rudimentary experiences. Observe the falling of heavy 

 ruin-drops into a tranquil pond. Each drop as it strikes 



