Death is a distressing thing to contemplate under any circumstances, and not less so to a philosopher when that of a whole world is concerned. To think that this fair globe with all it has brought forth must lapse in time to nothingness; that the generations of men shall cease to be, their very records obliterated, is something to strike a chill into the heart of the most callous and numb endeavor at its core. That æons must roll away before that final day is to the mind of the far-seeing no consolation for the end. Not only that we shall pass, but that everything to show we ever were shall perish too, seems an extinction too overpowering for words. But vain regret avails not to change the universe’s course. What is concerns us and what will be too. From facing it we cannot turn away. We may alleviate its poignancy by the thought that our interest is after all remote, affecting chiefly descendants we shall never know, and commend to ourselves the altruistic example so nobly set us by doctors of medicine who, on the demise of others at which—and possibly to which—they have themselves assisted, show a fortitude not easily surpassed, a fortitude extending even to their bills. If they can act thus unshaken at sight of their contemporaries, we should not fall behind them in heroism toward posterity. Having in our last chapter run the gantlet of the geologists, we are in some sort fortified to face death—in a world—in this. The more so that we have some millenniums of respite before the execution of the decree. By the death of a planet we may designate that stage when all change on its surface, save disintegration, ceases. For then all we know as life in its manifold manifestations is at an end. To this it may come by many paths. For a planet, like a man, is exposed to death from a variety of untoward events. Of these the one least likely to occur is death by accident. This, celestially speaking, is anything which may happen to the solar system from without, and is of the nature of an unforeseen catastrophe. Our Sun might, as we remarked, be run into. For so far as we know at present the stars are moving among themselves without any too careful regard for one another. The swarm may be circling a central Sun as André states, but the individual stars behave more like the random particles of a gas with licensed freedom to collide; whereas we may liken the members of the solar system to molecules in the solid state held to a centre from which they can never greatly depart. Their motions thus afford a sense of security lacking in the universe at large.