Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/240

 nothing against one that should affirm, that the principle of the circular motions of grave and light bodies is an intern accident: I know not how he may prove, that it cannot be a substance.

He brings many Arguments against this. The first of which is in these words: Si secundum (nempè, si dicas tale principium esse substantiam) illud est aut materia, aut forma, aut compositum. Sed repugnant iterum tot diversæ rerum naturæ, quales sunt aves, limaces, saxa, sagittæ, nives, fumi, grandines, pisces, &c. quæ tamen omnia specie & genere differentia, moverentur à naturà suâ circulariter, ipsa naturis diversissima, &c. [In English thus] If the second, (that is, if you shall say that this principle is a substance) it is either matter, or form, or a compound of both. But such diverse natures of things are again repugnant, such as are birds, snails, stones, darts, snows, smoaks, hails, fishes, &c. all which notwithstanding their differences in species and kind, are moved of their own nature circularly, they being of their natures most different, &c.

If these things before named are of diverse natures, and things of diverse natures cannot have a motion in common, it must follow, if you would give satisfaction to all, that you are to think of, more than two motions onely of upwards and downwards: and if there must be one for the arrows, another for the snails, another for the stones, and another for fishes; then are you to bethink your self of worms, topazes and mushrums, which are not less different in nature from one another, than snow and hail.

It seems that you make a jest of these Arguments.

No indeed, Simplicius, but it hath been already answered above, to wit, that if one motion, whether downwards or upwards, can agree with all those things afore named, a circular motion may no less agree with them: and as you are a Peripatetick, do not you put a greater difference between an elementary comet and a celestial star, than between a fish and a bird? and yet both those move circularly. Now propose your second Argument.

Si terra staret per voluntatem Dei, rotaréntne cætera, an non? si hoc, falsum est à naturâ gyrare; si illud, redeunt priores quæstiones. Et sanè mirum esset, quòd Gavia pisciculo, Alauda nidulo suo, & corvus limaci, petraque, etiam volans, imminere non posset. [Which I thus render:] If the Earth be supposed to stand still by the will of God, should the rest of bodies turn round or no? If not, then it's false that they are revolved by nature; if the other, the former questions will return upon us. And truly it would be strange that the Sea-pie should not be able to hover over the small fish, the Lark over her nest, and the Crow over the snail and rock, though flying.