TIME AND CHANGE 
doubtless made him the victim of diseases to which 
the lower orders, and even savage man, are strang- 
ers. Will not these diseases increase as his life be- 
comes more and more complex and artificial? Will 
he go on extending his mastery over Nature and re- 
fining or suppressing his natural appetites till his 
original hold upon life is fatally enfeebled? 
It seems as though science ought to save man and 
prolong his stay on this planet, — it ought to bring 
him natural salvation, as his religion promises him 
supernatural salvation. But of course, man’s fate 
is bound up with the fate of the planet and of the 
biological tree of which he is one of the shoots. 
Biology is rooted in geology. The higher forms of 
life did not arbitrarily appear, they flowed out of 
conditions that were long in maturing; they flow- 
ered in season, and the flower will fall in season. 
Man could not have appeared earlier than he did, 
nor later than he did; he came out of what went be- 
fore, and he will go out with what comes after. His 
coming was natural, and his going will be natural. 
His period had a beginning, and it will have an end. 
Natural philosophy leads one to affirm this; but of 
time measured by human history he may yet havea 
lease of tens of thousands of years. 
The hazard of the future is a question of both 
astronomy and geology. That there are cosmic 
dangers, though infinitely remote, every astronomer 
knows. That there are collisions between heavenly 
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