SECT. I.
TO remove the Doubt or Scruple that be∣gan to be discoursed of just before we last parted, I shall need to do little more than enlarge the Particulars, which (you know) I had then time but briefly to make men∣tion of. For the state of the Question was, (as you may remember) this, Whether there be among Bodies Page 2 any absolute Rest? On which occasion I answered, That Rest being a word that to me seem'd somewhat ambigu∣ous, I thought 'twas requisite to clear the sense of the Question before I offer'd at answering it.
For the word Rest, when we speak of distinct Masses of Matter, lookt upon as quiescent, does in the vulgar acception of the Term signifie, such a state of a visible and entire Body, or (rather) of the Corpuscles it con∣sists of, that they are actually Vnmoved as to sight; the Eye (and perhaps not the Touch) being not able to dis∣cern any local Motion in them.
Consonantly to this first Member of the distinction of the word Rest, I briefly intimated to the Company, that in this sense of a Corpuscles being at Rest, I thought it manifest, that there is such a thing in Rerum Natura: Since without granting such a Rest in the component Particles of some kind of Bodies, as Diamonds, Iron, Porphiry, &c. 'twill be (I conceive) very hard to ex∣plain, how there can be such solid Masses (as those Mine∣rals are) made up of small and separable Particles. Which being said, I added, that I saw no reason why such a kind of firmness, where the inward motion of the insensible Particles is almost infinitely slow, may not suffice to give an account of as great a firmness as we use really to find among consistent Bodies.
But whereas I had intimated to the Company, by the lately begun Distinction, that besides this popular sense of the word Rest, there was a second, more rigid and Philosophical Notion, or kind of Rest, which for distin∣ction sake may be called Absolute or Perfect Rest; which imports a continuance of a Body in the same place precisely, and includes an absolute Negation of all local Motion, though never so slow or imperceptible; I told them that in this rigid sense of the word Rest, I durst not affirm, that there are any Bodies at Rest in the Page 3 Universe (at least for any long time) but willingly al∣lowed it to be made a Problem, whether there be any or no: adding, that perhaps I enclin'd to the Negative part of the Question.
Having thus historically summ'd up what pass'd be∣twixt us about the state of the Controversie, I need not tell you, that the Doubt I express'd was thought to re∣lish too much of a Paradox; and therefore since the company's quick separation allow'd me then no oppor∣tunity of enlarging, and since I promis'd no better Ar∣guments than might be expected in a point that I pro∣pos'd but as Problematical; I shall now endeavour to shew you that the side of the Problem I was judg'd en∣clin'd to, is (at least) not so improbable as some thought it.
To prove Negatives directly, being wont (as you well know) to be no easie Task, and especially in such cases as this; you will not, I presume, expect that I should attempt the proving of my Conjecture otherwise than by shewing positively, that some of those Bodies which we think to have their parts most at Rest, are not exempted from having Intestine Motions in them; since 'twill be consequent to such a proof, that it must be pro∣bable, that in other Bodies whose Solidity is confessed to be inferiour, the component Particles are not in a state of Perfect Rest.
