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 flowered 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 before, 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 have a 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 bodies is an indubitable fact, and if collisions do happen to any, allow time enough and they must happen to all. That there are geologic dangers through the shifting and crumpling of the earth's crust, every geologist knows, though probably none that could wipe out the whole race of man. The biologic dangers of the past we have outlived--the dangers that must have beset a single line of descent amid the carnival of power and the ferocity of the monster reptiles of Mesozoic times, and the wholesale extinction of species that occurred in different geologic periods. Nothing but a cosmic catastrophe, involving the fate of the whole earth, could now exterminate the human race. It is highly improbable that this will ever happen. The race of man will go out from a slow, insensible failure, through the aging of the planet, of the conditions of life that brought man here. The evolutionary process upon a cooling world must, after the elapse of a vast period of time, lose its impetus and cease. XIII THE GOSPEL OF NATURE I The other day a clergyman who described himself as a preacher of the gospel of Christ wrote, asking me to come and talk to his people on the gospel of Nature. The request set me to thinking whether or not Nature has any gospel in the sense the clergyman had in mind, any message that is likely to be specially comforting to the average orthodox religious person. I suppose the parson wished me to tell his flock what I had found in Nature that was a strength or a solace to myself.