Then for “physics,” that is, the knowledge of the subordinate and secondary causes of natural events; they render none at all, but empty words. If you desire to know why some kind of bodies sink naturally downwards toward the earth, and others go naturally from it, the schools will tell you out of Aristotle, that the bodies that sink downwards are “heavy,” and that this heaviness is it that causes them to descend. But if you ask what they mean by “heaviness,” they will define it to be an endeavour to go to the centre of the earth. So that the cause why things sink downward, is an endeavour to be below; which is as much as to say, that bodies descend, or ascend, because they do. Or they will tell you the centre of the earth is the place of rest, and conservation for heavy things; and therefore they endeavour to be there: as if stones and metals had a desire, or could discern the place they would be at, as man does; or loved rest, as man does not; or that a piece of glass were less safe in the window than falling into the street.