What shadows would be if there were no bodies, such natural motion in the upper regions will become, without levity. For, of a truth, it would be mon… - Jean Rey

I imagine there are many persons who would have been startled (effarouchées) at the mere statement of this answer, had I given it in the outset, that will now receive it willingly, being, as I may say, tamed (apprivoisées) and rendered tractable, by the evident truth of the preceding essays. For doubtless they whose minds were preoccupied with the opinion that air is absolutely light, would have rushed to the encounter, exclaiming, Why do we not extract heat from cold, white from black, light from darkness, if from air, a thing absolutely light, we can extract so much weight? And they, who might have given credit to the weight of air, would have been unable to persuade themselves, that it could ever increase the weight of a substance balanced in itself.

On this account I have been obliged to shew, that air is possessed of weight; that it is proved by other investigation than that of the balance; and that even by that instrument, a portion previously altered and thickened, may make its weight manifest.

With regard to the celestial heat making bodies light, Scaliger very properly objects that the heavens, which abound in this heat, as being the source of it, must be light (feut leger) and consequently univocal (univoque) with the other bodies, which is absurd.