413 THE THEORY OF THE FIRMAMENT. that twofold principle of pure air and constellation he not put off, nor yet flame extended to the heaven of heavens. It affirms that stars are real flames, but that the actions of flame in the heavens should in no wise be wrested into a comparison with the actions of flame with us, most of which operate by casualty. It affirms that the ether interspersed among stars, and the stars themselves, have re spective relations to air and flame, but sublimated and rectified. And thus, with respect to the sub stance of the constitution or system of the uni verse, some such ideas as these have suggested themselves to our mind. We must now speak of the motions of the neavenly bodies, on account of which we have adduced these premises. It appears reasonable to suppose that rest is not excluded from nature as to any whole, (for we are not now discoursing of small parts.) This (waiving logical and mathematical subtleties) is mainly evident from the fact, that the inciting causes, and the veloci ties of the heavenly motions, gradually slacken themselves, as tending to ultimate cessation, and because that, even the heavenly bodies partake of rest, hard by the poles, and because, if immo bility be excluded the system, it is dissolved and dissipated. But, if there be a certain accumula tion and mass of matter of an immovable nature, there seems no further room to doubt that it is the globe of the earth ; for a dense and close cement ing of matter disposes toward a languid and reluctant motion ; as, on the contrary, a loose unfolding of it towards a brisk and ready one. And not without reason did Telesius (who revived the philosophy and discussions of Parmenides in a treatise on the principle of cold,) introduce into nature, not, indeed, a co-essentiality and coupling, (which was his wish,) but, however, an affinity and agreement, to wit, on one side, of hot, shining, rare, and immovable, and, on the opposite part, of cold, dark, dense, and immovable, by placing the site of the first harmony in the heavens, of the second on the earth. But, if rest and immo bility be conceded, it seems fit that we also sup pose a motion without limit and to the uttermost movable, especially in natures opposed to each other. This motion is commonly rotatory, such as is generally found in the heavenly bodies ; for, motion in a circle has no termination, and seems to flow from a natural desire of the body, which moves, only that it may move, and follow itself, and seek its own embraces, and excite its nature, and enjoy it, and exercise itself in its proper ope ration ; whereas, a motion in a right line may seem a finite journeying, and a movement to a boundary I of cessation or rest, and that it may attain some thing, and then quietly lay down its motion. Wherefore, respecting that rotatory motion, which motion is true and perennial, and commonly sup posed peculiar to the heavenly bodies, we must inquire how it equips itself in the outset, and by what rate of conduct it incites and checks itsel r and what the nature may be of those influences which really act upon it. In our progress of un folding these things, we will refer to computations and tables, that beautiful mathematical dogma, (that all motions are restrained to circles, per fect, or eccentric, or concentric,) and that high flown dictum, (that the earth is, in respect of the firmament, like a point of no magnitude,) and many more feigned discoveries of astronomers. But, first, we will divide the heavenly motions : some are cosmici, others, ad invicem. Those we call cosmici, which the heavenly bodies acquire from the consent not only of the heavens, but of the universe: those ad invicem, in which some heavenly bodies depend on others: and this is a true and necessary division. On the supposition, then, of the earth standing still, (for that, at pre sent, appears to us the truer hypothesis,) it is manifest that the heavens are carried round by a diurnal motion, the measure of which motion is the space of twenty-four hours, or thereabouts ; and, consequently, the revolution is from east to west, upon certain points, (which they call poles,) south and north : moreover, the heavens are not whirled round movable poles, nor, back again, are the points different from those stated : and this motion verily seems in harmony with uni versal nature, and therefore sole, except as far as it admits both of decrements and declinations ; according to which decrements and declinations, this motion shoots through every thing movable, and pervades all space, from the constellated firmament even to the very bowels and inmost recesses of the earth ; not by any snatched or harassing course, but by perpetual consent; and that motion in the constellated firmament is perfect and entire, as well as to a just measure of time, as by a full restoration of place; but, inas much as that motion recedes from the summit of the heavens, insomuch does it become more im perfect, with a reference to its slowness as well as its aberration from a circular motion. And, first, we must speak distinctly of that slowness. We affirm, that the diurnal motion of Saturn is too slow to carry it round, and restore it to the same point in twenty-four hours; but that the starry firmament is carried on quicker, and out strips Saturn by such an excess, as, in as many days as complete thirty years, would agree with a whole circuit of the heavens. The same is to be said of the rest of the planets, according to the difference of the periodic time of each planet; so that the diurnal motion of the starry firmament (in that same period, without any regard to the magnitude of the circle) is nearly by one hour swifter than the diurnal motion of the moon; for, if the moon could complete its revolution in twenty-four days, then that excess would be one whole hour; wherefore that much talked of mo tion, in an opposite and contrary direction, from
