SCIENTIFIC USE OF THE IMAGINATION. 155 



doubt in the matter, it ought to be given in favor of the 

 freedom of such a mind. To it a vast possibility is in it- 

 self a dynamic power, though the possibility may never 

 be drawn upon. It gives me pleasure to think that the 

 facts and reasonings of this discourse tend rather toward 

 the justification of Mr. Darwin than toward his condemna- 

 tion, that they tend rather to augment than to diminish the 

 cubic space demanded by this soaring speculator ; for they 

 seem to show the perfect competence of matter and force, 

 as regards divisibility and distribution, to bear the heaviest 

 strain that he has hitherto imposed upon them. 



In the case of Mr. Darwin, observation, imagination, and 

 reason combined, have run back with wonderful sagacity 

 and success over a certain length of the line of biological 

 succession. Guided by analogy, in his " Origin of Species," 

 he placed at the root of life a primordial germ, from which 

 he conceived the amazing richness and variety of the life 

 that now is upon the earth's surface might be deduced. If 

 this hj^pothesis were true, it would not be final. The hu- 

 man imagination would infallibly look behind the germ, 

 and, however hopeless the attempt, would inquire into the 

 history of its genesis. In this dim twilight of conjecture 

 the searcher welcomes every gleam, and seeks to augment 

 his light by indirect incidences. He studies the methods 

 of Nature in the ages and the worlds within his reach, in 

 order to shape the course of speculation in the antecedent 

 ages and worlds. And though the certainty possessed by 

 experimental inquiry is here shut out, the imagination is 

 not left entirely without guidance. From the examination 

 of the solar system, Kant and Laplace came to the conclu- 

 sion that its various bodies once formed parts of the same 

 undislocated mass ; that matter in a nebulous form preceded 

 matter in a dense form ; that as the ages rolled away, heat 

 was wasted, condensation followed, planets were detached, 

 and that finally the chief portion of the fiery cloud reached, 



