SECT.  LXXVIII.  The Suppositions of the Epicureans are False and Chimerical.

Must we suppose, besides, that atoms have motion of themselves?  Shall we suppose it out of gaiety to give an air of reality to a system more chimerical than the tales of the fairies?  Let us consult the idea we have of a body.  We conceive it perfectly well without supposing it to be in motion, and represent it to us at rest; nor is its idea in this state less clear; nor does it lose its parts, figure, or dimensions.  It is to no purpose to suppose that all bodies are perpetually in some motion, either sensible or insensible; and that though some parts of matter have a lesser motion than others, yet the universal mass of matter has ever the same motion in its totality.  To speak at this rate is building castles in the air, and imposing vain imaginations on the belief of others; for who has told these philosophers that the mass of matter has ever the same motion in its totality?  Who has made the experiment of it?  Have they the assurance to bestow the name of philosophy upon a rash fiction which takes for granted what they never can make out?  Is there no more to do than to suppose whatever one pleases in order to elude the most simple and most constant truths?  What authority have they to suppose that all bodies incessantly move, either sensibly or insensibly?  When I see a stone that appears motionless, how will they prove to me that there is no atom in that stone but what is actually in motion?  Will they ever impose upon me bare suppositions, without any semblance of truth, for decisive proofs?