But to convince us, that all the Laws of Nature and all the Operations of Bodies, without Exception, are known only by Experience, the following Reflections may, perhaps, suffice. Were any Object presented to us, and were we requir'd to pronounce concerning the Effect, that will result from it, without consulting past Observation; after what Manner, I beseech you, must the Mind proceed in this Operation? It must invent or imagine some Event, which it ascribes to the Object as its Effect; and 'tis plain this Invention must be entirely arbitrary. It can never possibly find the Effect in the suppos'd Cause, by the most accurate Scrutiny and Examination. For the Effect is totally different from the Cause, and consequently can never be discover'd in it. Motion in the second Billiard-ball is a quite distinct Event from Motion in the first; nor is there any thing in the one to suggest the smallest Hint of the other. A Stone or Piece of Metal rais'd into the Air, and left without any Support, immediately falls: But to consider the Matter a priori; is there any thing we discover in this Situation, which can beget the Idea of a downward, rather than an upward, or any other Motion, in the Stone or Metal?
And as the first Imagination or Invention of a particular Effect, in all natural Operations, is arbitrary,where
