Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/80

 Rather how improper, for being by its transparence, wholly invisible, a man would not be able without stumbling at the thresholds, and breaking his head against the Walls, to pass from room to room.

This danger would not befall him, if it be true, as some Peripateticks say, that it is intangible: and if one cannot touch it, much less can it hurt him.

This would not serve the turn, for though the matter of the Heavens cannot be touch, as wanting tangible qualities: yet may it easily touch the elementary bodies; and to offend us it is as sufficient that it strike us, nay worse, than if we should strike it. But let us leave these Pallaces, or, to say better, these Castles in the air, and not interrupt Simplicius.

The question which you have so casually started, is one of the most difficulty that is disputed in Philosophy; and I have on that subject most excellent conceits of a very learned Doctor of Padoua, but it is not now time to enter upon them. Therefore returning to our purpose, I say that the Moon, in my opinion, is much more solid than the Earth, but do not infer the same, as you do, from the cragginess and montuousity of its superficies; but rather from the contrary, namely, from its aptitude to receive (as we see it experimented in the hardest stones) a polish and lustre exceeding that of the smoothest glass, for such necessarily must its superficies be, to render it apt to make so lively reflection of the Suns rays. And for those appearances which you mention, of Mountains, Cliffs, Hills, Valleys, &c. they are all illusions: and I have been present at certain publick disputes, where I have heard it strongly maintained against these introducers of novelties, that such appearances proceed from nothing else, but from the unequal distribution of the opacous and perspicuous parts, of which the Moon is inwardly and outwardly composed: as we see it often fall out in chrystal, amber, and many other precious stones of perfect lustre; in which by reason of the opacity of some parts, and the transparency of others, there doth appear several concavities and prominencies. In the fourth resemblance, I grant, that the superficies of Terrestrial Globe beheld from afar, would make two different appearances, namely, one more clear, the other more dark; but I believe that such diversity would succeed quite contrary to what you say; that is, I hold that the surface of the water would appear lucid, because that it is smooth and transparent; and that of the Earth would appear obscure, by reason of its opacity and scabrosity, ill accommodated for reflecting the light of the Sun. Concerning the fifth comparison, I grant it wholly, and am able, in case the Earth did shine as the Moon, to show the same to any one that should from thence above behold it, repre-