Neither can the loss of this heat render them heavy, for I have already proved that nothing increases in weight but by the addition of matter, or by … - 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.

This opinion is defective, to say no worse of it, in many respects. First, in attributing life to lead. Secondly, in supposing that the presence of the celestial heat makes it light, and its absence heavy. Thirdly, because it assigns the same reason for the increased weight of lead by calcination, and of animals by death. There is nothing of the kind. For as to life, how can lead possess it, since it is a homogeneous body, without difference of parts, without organs, and without any vital effect or action? If it move downwards, so does ceruse, which is only its corpse; if it be cooling (rafraischit), so is ceruse. Then how could it preserve this life, under a million of forms, that it may be made to assume and to cast off, yet always continuing to be lead? How, in the furnace (which would be a much greater wonder), where it may be kept in fusion a day, a month, or a whole year? It must have a very tenacious soul to undergo so much without being dislodged!

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.