"I say much more; that fire, being of so subtile a nature, that it can hardly be called a body, is consequently almost stripped of all resistance; whence it follows, that the air, mounting up without impediment, would reach the skies, driving fire from its place, and compelling it to seek a lower station, to the injury of their own doctrine. To this I will add another inconvenience, namely, the perpetual and unprofitable strife, which would ensue between the heavy and the light elements, the latter pulling upwards, and the former downwards, with all their might; whence would arise, at the place of their contiguity, incomparably greater distress than the packthread experiences which is pulled in opposite directions by two strong hands, till at last it is broken by their efforts: far different from that knot of friendship, in which nature has been pleased to unite the neighbouring elements, planting in their bosoms similar qualities, whence they communicate and amicably sympathize with each other. It follows from all this, that levity is a term that signifies nothing absolute in nature, and must be rejected; or, if we retain it, it must only be to denote the relation of one substance having less weight to another which has more."