DEVONIAN FISHES OF IOWA 37 



pardoned the digression, let us reflect for a moment on the far- 

 reaching consequences of the Copernican conception of the 

 world, one of the profoundest of all reorganizing ideas. Place 

 alongside of it Newton's theory of gravitation, which gave for all 

 time a definite and demonstrated system of the universe, and to 

 these two add Darwin's theory of descent — that is, of organic 

 evolution — we shall then have the leading factors which have 

 immeasurably extended the material world in modern times, and 

 vastly enlarged our horizon. Through their medium our ideas 

 of space, durations and existence have acquired new validity, 

 present a surprisingly larger manifold, and disclose to cognition 

 unfathomable riches. If it be true, as Pascal says, that "all our 

 dignity consists in thought," how greatly have the boundaries 

 of our mental vision been widened and illumined, thanks to these 

 three revolutionary ideas. 



To illustrate: We all know, for instance, that the ancient 

 conception of the world was strictly limited. For the ancient and 

 mediaeval man our earth stood at the middle of the world, and the 

 vault of heaven, supposed to be not distantly removed, formed 

 the outermost limit of creation. The Homers and Dantes of their 

 time have pictured to us what a comfort and support this limited 

 world-conception yielded to human imagination. But so soon as 

 Copernicus had shown that the simplest way to conceive the 

 world was to think of the earth as an unsupported ball revolving 

 about the sun, both being lost in limitless space, our planet could 

 no longer occupy the center of the universe, and the satisfying 

 framework which had supported the old cosmography was shat- 

 tered in pieces. Religion itself received a violent shock as the 

 thought gained ground that the human race was by no means the 

 goal and acme of the universe. The established faith revolted 

 at the idea of ultimate extinction of man and all his works, and 

 repudiated whatever reasoning gave countenance to the pre- 

 diction. 



Before the era of modern science had begun, leaders of public 

 opinion were satisfied on the basis of traditional or preconceived 

 ideas to explain what man is, whence he came, whither he is 

 bound, what he may become, and what he should be. Armed 

 with new truths, and enriched by a vast supply of demonstrated 



