Whether the economy of the globe is circular, or not, I am not in a position to show. But its movements certainly are; and so are the movements of all the myriad worlds with which astronomy is conversant. Asteroids, planets, satellites, comets, suns,--nay, even the stellar universe itself--obey _in their motions_, the grand universal law of circularity. Take any one of these;--our Moon. When its orbital motion commenced, it commenced at some point or other of the circle which it describes in its course around the earth. The pre-existence, or at least the co-existence, of the Earth, and also that of the Sun, are necessary to its motion. Supposing it possible for a spectator, furnished with modern astronomical knowledge, to have looked at that instant on the newly-spun orb, would he not confidently have inferred, from its position at that moment, its position a week before? Would he not have felt able to indicate with unhesitating certainty the solar and lunar eclipses of a century or a chiliad before, just as he now calculates the time of the eclipse that marked the death of Herod the Great? Undoubtedly he would; for he would assume the constancy of those movements which modern science has deduced from the observations of many centuries; and, granting him the fact of their constancy, we could not invalidate his conclusions. Yet _what_ would he have shown? The conditions and phenomena of bodies before they had begun to exist. The conditions are legitimately deducible; but they are prochronic conditions. The mention of the celestial orbs suggests to remembrance the famous argument for the vast antiquity of the material universe, founded on the time which is required for the propulsion of light. I believe it owes its origin to Sir William Herschel. Speaking of the known velocity of light in connexion with the immense distance of certain nebulae, that eminent astronomer made these remarks:-- "Hence it follows, that, when we... see an object of the calculated distance at which one of these very remote nebulae may still be perceived... the rays of light which convey its image to the eye must have been more than nineteen hundred and ten thousand, that is, almost _two millions_, of years on their way; and that, consequently, so many years ago, this object must already have had an existence in the sidereal heavens, in order to send out those rays by which we now perceive it."[107] The notion has been amplified, with some interesting details, by a writer in the _Scottish Congregational Magazine_ for _January 1847_; who thus throws the statements into a tabular form, and comments on them.