A Century of Science 13 



to be an Eocene world, and so on, until the aspect 

 of the world that we know to-day should noise- 

 lessly steal upon us. 



When once the truth of Ly ell's conclusions be- 

 gan to be distinctly realized, their influence upon 

 men's habits of thought and upon the drift of 

 philosophic speculation was profound. The con- 

 ception of Evolution was irresistibly forced upon 

 men's attention. It was proved beyond question 

 that the world was not created in the form in which 

 we find it to-day, but has gone through many 

 phases, of which the later are very different from 

 the earlier ; and it was shown that, so far as the 

 inorganic world is concerned, the changes can be 

 much more satisfactorily explained by a reference 

 to the ceaseless, all-pervading activity of gentle, un- 

 obtrusive causes such as we know than by an ap- 

 peal to imaginary catastrophes such as we have no 

 means of verifying. It began to appear, also, that 

 the facts which form the subject-matter of different 

 departments of science are not detached and inde- 

 pendent groups of facts, but that all are intimately 

 related one with another, and that all may be 

 brought under contribution in illustrating the his- 

 tory of cosmic events. It was a sense of this inter- 

 dependence of different departments that led Au- 

 guste Comte to write his " Philosophie Positive," the 



