the earth, which is of a lesser quantity, should be appointed to such a motion as is somewhat proportionable to its bigness, than that the heavens that are of such a vast magnitude, should be whirled about with such an incredible swiftness, which does as far exceed the proportion of their bigness, as their bigness does exceed this earth, that is but a point or centre to them. It is not likely that nature in these constant and great works, should so much deviate from that usual harmony and proportion which she observes in lesser matters. If this globe of earth only were appointed to move every day round the orb of the fixed stars, though it be but a little body, and so more capable of a swift motion; yet that swiftness would be so extremely disproportionable unto it, that we could not with reason conceive it possible, according to the usual course of nature. But now that the heavens themselves, of such strange bigness, with so many stars, which do so far exceed the magnitude of our earth, should be able to turn about with the same celerity, oh! it is altogether beyond the fancy of a poet or a mad man. For answer unto this argument, our adversaries tell us: that there is not in the heavens any repugnancy to so swift a motion; and that whether we consider the nature of those bodies; or, secondly, the swiftness of this motion. I. For the nature of those bodies, either Qualities. their Quantity. 1. There is not in them the qualities of lightness or heaviness, or any the least contrariety that may make them reluctant to one another. 2. Their magnitude will help them in their swiftness * : for the greater any body is, the quicker will it be in its motion, and that not only when it is moved by an inward principle, as a millstone will descend faster than a little pebble; but also when its motion does proceed from some external agent; as the wind will drive a great cloud, or a heavy ship, when it is not able to stir a little stone. Ross. 1. 1. sect. 1. c. i. II. As for the swiftness of this motion, the possibility of it may be illustrated by other particulars in nature: as, 1. The sound of a cannon, in a little time is carried for twenty miles distance *. 2. Though a star be situated so remotely from us, yet the eye discerns it in a moment, which is not without some motion, either of the species of the star, or the rays of the eye. Thus also the light does in an instant pass from one side of the heaven to another ↑. I. If the force of powder be able to carry a bullet with so great a swiftness, we need not doubt then, but that the heavens are capable of such a celerity as is usually attributed unto them. Unto these it may be answered: 1. Where they say that the heavenly bodies are without all gravity, we grant it, in the same sense as our earth also, being considered as whole, and in its proper place, may be denied to be heavy: Since this quality in the exactest sense, can only be ascribed unto such parts as are severed from the whole to which they belong. But however, since the heavens or stars are of a material substance, it is impossible but there should be in them some ineptitude to motion; because matter is of itself a dull and sluggish thing, and by so much the more, as it is kept close and condensed together. And though the followers of Ptolemy do with much confidence deny the heavens to be capable of any reluctancy to motion, yet it were easy to prove the contrary out of their own principles. It is not conceivable how the upper sphere should move the nether, unless their superficies were full of rugged parts (which they deny): or else one of the orbs must lean upon the other with its weight, and so make it partake of its own motion. And besides, they tell us, that the farther any sphere is distant from the primum mobile, the less it is hindered by that in its proper course, and the sooner does it finish its own revolution. Ross, 1. 2. sect. 1. c. 5. + Idem, 1. 1. sect. 1. 2. From whence it will easily follow, that these bodies have resistency from one another. I have often wondered why amongst the enchanted buildings of the poets, they have not feigned any castle to be made of the same materials with the solid orbs, since in such a fabric there would have been these eminent conveniences. 1. It must needs be very pleasant, by reason of its perspicuity, because it is more diaphanous than the air itself, and so the walls of it could not hinder the prospect any way. 2. Being so solid and impenetrable, it must needs be excellent against all violence of weathers, as also against the assaults of the enemy, who should not be able to break it with the most furious batteries of the ram, or pierce it with any cannon shot. 3. Being void of all heaviness, a man may carry it up and down with him, as a snail does his house; and so whether he follow the enemy, or fly from him, he has still this advantage, that he may take his castle and defence along with him. But then again, there are on the other side as many inconveniencies. For, 1. Its perspicuity would make it so open, that a man should not be able to retire himself into any private part of it. And then, 2. Being so extremely solid, as well as invisible, a man should be still in danger of knocking his head against every wall and pillar; unless it were also intangible, as some of the peripatetics affirm. 3. Its being without all gravity, would bring this inconvenience, that every little puff of wind would blow it up and down; since some of the same sect are not ashamed to say, that the heavens are so utterly devoid of heaviness, that if but a little fly should jostle against the vast frame of the celestial spheres, he would move them out of their places. A strong fancy, that could be at leisure, might make excellent sport with this astronomical fiction. So that this first evasion of our adversaries will not shelter them from the force of that argument, which is taken from the incredible swiftness of the heavens. 2. Whereas they tell us in the second place, that a bigger body, as a millstone, will naturally descend swifter than 2 less, as a pebble. I answer: this is not because such a great body is in itself more easily moveable, but because the bigger any thing is which is out of its own place, the stronger will be its natural desire of returning thither, and so consequently, the quicker its motion. But now those bodies that move circularly, are always in their proper situations, and so the same reason is not appliable unto them. And then, whereas it is said, that magnitude does always add to the swiftness of a violent motion (as wind will move a great ship sooner than a little stone: we answer: this is not because a ship is more casily moveable in itself than a little stone: for I suppose the objector will not think he can throw the one as far as the other; but because these little bodies are not so liable to that kind of violence from whence their motion does proceed. As for those instances, which are cited to illustrate the possibility of this swiftness in the heavens, we answer: the passage of a sound is but very slow in comparison to the motion of the heavens. And then besides, the swiftness of the species of sound or sight which are accidents, are not fit to infer the like celerity in a material substance: and so likewise for the light which Aristotle himself *, and with him the generality of philosophers, do for this very reason prove not to be a body, because it moves with such swiftness, of which (it seems) they thought a body to be incapable. Nay, the objector † himself in another place, speaking of light in reference to a substance, does say: Lumen est accidens, sic species rei visa, & alia est ratio substantiarum, alia accidentium. To that of a bullet, we answer: he might as well have illustrated the swiftness of a bullet, which will pass four or five miles in two minutes, by the motion of a hand in a Ross. 1. 2. sect. 1. c. 4. * De Anima, 1. 2. c. 7. watch, which passes two or three inches in twelve hours; there being a greater disproportion betwixt the motion of the heavens and the swiftness of a bullet, than there is betwixt the swiftness of a bullet and the motion of a hand in a watch. Another argument to this purpose may be taken from the chief end of the diurnal and annual motions, which is to distinguish betwixt night and day, winter and summer; and so consequently, to serve for the commodities and seasons of the habitable world. Wherefore it may seem more agreeable to the wisdom of providence, for to make the earth as well the efficient, as the final cause of this motion; especially since nature in her other operations does never use any tedious difficult means to perform that which may as well be accomplished by shorter and easier ways. But now, the appearances would be the same, in respect of us, if only this little point of earth were made the subject of these motions, as if the vast frame of the world, with all those stars of such number and bigness were moved about it. It is a common maxim, Μηδεν είχη την φυσιν εργάζεσθαι *. Nature does nothing in vain, but in all her courses does take the most compendious way. It is not therefore (I say) likely, that the whole fabric of the heavens, which do so much exceed our earth in magnitude and perfection, should be put to undergo so great and constant a work in the service of our earth, which might more easily save all that labour by the circumvolution of its own body; especially, since the heavens do not by this motion attain any farther perfection for themselves, but are made thus serviceable to this little ball of earth. So that in this case it may seem to argue as much improvidence in nature to employ them in this motion, as it would in a mother †, who in warming her child, would rather turn the fire about that, than that about the fire or in a cook ‡, who would not roast his meat by turning it about to the fire; but rather, by turning the fire about it or in a man |, who ascending some high tower, to * Galen. + Lansberg. + Keplar. || Galil. |