There are, however, what I may call "leapers" in the system, which, without the use of a pole, are able to cross this gulf; they are THE COMETS. These comets are, as a rule, so thin--a mere filmy mass of vapor--that when they come flashing into our system, and rushing out again, as they do, they never disturb the motion of a planet. And there are some terrestrial comets about, that I know, that go to various towns, and blaze away for a time; but they have no power to disturb the planets revolving there in their regular course. The power of a man does not consist in rushing to and fro, like a comet, but in steadily shining year after year, like a fixed star. The astronomer Halley says: "If you were to condense a comet down to the thickness of the ordinary atmosphere, it would not fill a square inch of space." So thin is a comet that you might look through five thousand miles of it, and see just as easily as if it were not there. It is well to be transparent, brethren; but I hope you will be more substantial than most of the comets of which we have heard. Comets come with great regularity, though they seem to be very irregular. Halley prophesied that the comet of 1682, of which little had been previously known, would return at regular intervals of about seventy-five years. He knew that he would not live to see its reappearance; but he expressed the hope that when it did return his prophecy might be remembered. Various astronomers were looking out for it, and they hoped it might arrive at the time foretold, because, otherwise, ignorant people would not believe in astronomy. But the comet came back all right; so their minds were set at rest, and Halley's prediction was verified. Among the stories concerning comet-watching, there is one that contains an illustration and a lesson also. "Messier, who had acquired the name of 'the comet-hunter,' from the number he discovered, was particularly anxious upon the occasion. Of great simplicity of character, his zeal after comets was often displayed in the oddest manner. While attending the death-bed of his wife, and necessarily absent from his observatory, the discovery of one was snatched from him by Montaigne de Limoges. This was a grievous blow. A visitor began to offer him consolation on account of his recent bereavement, when Messier, thinking only of the comet, answered, 'I had discovered twelve; alas, to be robbed of the thirteenth by that Montaigne!' But instantly recollecting himself, he exclaimed, 'Ah! cette pauvre femme!' and went on deploring wife and comet together." He evidently lived so much in the heavens that he forgot his wife; and if science can sometimes carry a man away from all the trials of this mortal life, surely our heavenly life ought to lift us up above all the distractions and cares that afflict us.