SCIENTIFIC USE OF THE IMAGINATION. 129 



alty would have been worse than failure. In some fashion 

 or other — feebly or strongly, meanly or manfully, on the 

 higher levels of thought, or on the flats of commonplace — 

 the task had to be accomplished. I looked in various direc- 

 tions for help and furtherance ; but without me for a time 

 I saw only " antres vast," and within me " deserts idle." 

 My case resembled that of a sick doctor who had forgotten 

 his art and sorely needed the prescription of a friend. Mr. 

 Bain wrote one for me. He said, " Your present knowl- 

 edge must forge the links of connection between what has 

 been already achieved and what is now required." ' In 

 these words he admonished me to review the past and re- 

 cover from it the broken ends of former investigations. I 

 tried to do so. Previous to going to Switzerland I had 

 been thinking much of light and heat, of magnetism and 

 electricity, of organic germs, atoms, molecules, spontaneous 

 generation, comets, and skies. With one or another of 

 these I now sought to reform an alliance, and finally suc- 

 ceeded in establishing a kind of cohesion between Thought 

 and Light. The wish grew within me to trace, and to en- 

 able you to trace, some of the more occult operations of 

 this agent. I wished, if possible, to take you behind the 

 drop-scene of the senses, and to show you the hidden mech- 

 anism of optical action. For I take it to be well worth 

 the while of the scientific teacher to take some pains, and 

 even great pains, to make those whom he addresses copart- 

 ners of his thoughts. To clear his own mind in the first place 

 of all haze and vagueness, and then to project into lan- 

 guage which shall leave no mistake as to his meaning — 

 which shall leave even his errors naked — the definite ideas 

 he has shaped. A great deal is, I think, possible to scien- 

 tific exposition conducted in this way. It is possible, I 

 believe, even before an audience like the present, to un- 

 cover to some extent the unseen things of Nature ; and 



1 Induction, p. 422. 



