WORLD-MAKING 35 



sediment the material accumulated by decay. Every change 

 of elevation was accompanied with changes of climate, and 

 with modifications of the habitats of animals and plants. 

 Were it possible to restore accurately the physical geography 

 of the earth in all these respects, for each geological period, 

 the data for the solution of many difficult questions would be 

 furnished. 



We have wandered through space and time sufficiently for 

 one chapter, and some of the same topics must come up later 

 in other connections. Let us sum up in a word. In human 

 history we are dealing with the short lives and limited plans of 

 man. In the making of worlds we are conversant with the 

 plans of a Creator with whom one day is as a thousand years, 

 and a thousand years as one day. We must not measure such 

 things by our microscopic scale of time. Nor should we fail 

 to see that vast though the ages of the earth are, they are parts 

 of a continuous plan, and of a plan probably reaching in space 

 and time immeasurably beyond our earth. When we trace the 

 long history from an incandescent fire-mist to a finished earth, 

 and vast ages occupied by the dynasties of plant and animal 

 life, we see not merely a mighty maze, an almost endless pro- 

 cession of changes, but that all of these were related to one 

 another by a chain of causes and effects leading onward to 

 greater variety and complexity, while retaining throughout the 

 traces of the means employed. The old rocks and the ancient 

 lines of folding and the perished forms of life are not merely a 

 scaffolding set up to be thrown down, but the foundation 

 stones of a great and symmetrical structure. Is it yet com- 

 pleted ? Who can tell ? The earth may still be young, and 

 infinite ages of a better history may lie before it. 

 REFERENCES l : Presidential Address to the American Association for the 

 Advancement of Science, meeting at Minneapolis, 1883. " The 

 Story of the Earth and Man." Ninth edition, London, 1887. 

 1 The references in this and succeeding chapters are exclusively to papers 

 and works by the author, on which the several chapters are based. 

 3 



