234 THE CHAIN OF LIFE. 



general and abstract truth. Objects are arranged, classified, 

 understood, and while in some respects the whole creation is 

 made to groan under the tyrannous inventions of man, yet 

 these are the inventions of imagination and design. They 

 are the triumph, not of brute force, but of will and 

 intelligence. 



That man was not in all the earlier ages of the world, except 

 in these prophecies of his coming, geology assures us. That he 

 is, we know. How he came to be, is, independently of Divine 

 revelation, an impenetrable mystery — one which it is doubtful if 

 in all its bearings science will ever be competent to solve. Yet 

 there are legitimate scientific questions of great interest relat- 

 ing to the time and manner of his appearance, and to the con- 

 dition of his earlier existence and subsequent history, which 

 belong to geology, and in which so great stores of material 

 have been accumulated that a treatise rather than a chapter 

 would be required for their discussion. We may endeavour 

 to select a few of the more important points. 



One of the first questions meeting us is that which relates 

 to the point in geological time signalise^ by the advent of our 

 species. In the Eocene period our continents were being gra- 

 dually raised out of the ocean, and were still in great part under 

 the waters, which several times returned upon the land, and 

 seemed ready again to engulf it. In this period not only have 

 we no traces of man, but all the higher animals of that age are 

 now extinct. In the later Eocene and Miocene the extent of 

 land became greater, but it was so disposed as to allow the 

 influx into the Arctic Sea of vast volumes of heated water from 

 the equatorial regions; and there may have been also astro- 

 nomical causes at work to increase this influx of warm water, 

 and so to raise the temperature of the Arctic regions still 

 higher.^ The middle period of the Tertiary was undoubtedly 

 a time very favourable to the wide distribution of the higher 

 forms of life both animal and vegetable. But we cannot trace 



^ Croll, Climate and Time. 



