II.

Motu im

that contented piece of ignorance, which attributes the CHAP. causes of every thing unto specific forms and occult qualities; for this is so shameful a piece of beggary, that P. Gassendus doth more than once disclaim it; and in his discourse of motion doth prove an impos- v. Ep. de sibility of motion in an infinite empty space. Might presso a not Epicurus then have saved his credit better by sit- translato, ting down with the opinions of his forefathers, than tom. iii.Op. thus to go a begging for such hypotheses, which none, who are not resolved to be ignorant, will be ready to grant him?

Motore

XV.

Præp.

But yet this is not all: but according to this fundamental principle of Epicurus, viz. that there is a principle of motion in every insensible particle of matter, he plainly overthrows another principle of his, which is, the solidity and different magnitude of these atoms. These particles are supposed so solid, that Dionysius in Eusebius tells us, the account given why they are Euseb. called ἄτομοι was, διὰ τὴν ἄλυτον στεῤῥότητα, because of Evang. 1. their indissoluble firmness; and the different sizes of xiv. c. 23. these atoms is so necessary a principle, that from thence they undertake to resolve many phenomena of the universe. Let us now see how consistent these things are with the inseparable property of motion belonging to atoms: for if there be particles of such different sizes, then it is plain that there are some particles which may not only be conceived to be bigger than others, but are really so; and so there must be more parts of matter imagined in this bigger particle than in another less; and if there be more parts, these parts may be conceived separate from each other, that this particle may be equal to the other. Now then I demand, if motion doth inseparably belong to the least particle of matter, how comes one to be bigger than the other? For herein we see that every particle is

III.

BOOK not in distinct motion: for there cannot but be more - imaginable particles in an atom of a bigger size than in a less; and if so, there must be some union of those imaginable particles in that bigger atom; and how could such an union be without rest, and what rest could there be, if motion doth inseparably belong to every particle of matter? And so it must be in all those atoms which are supposed to have angles and hooks, in order to their better catching hold of each other for the composition of bodies; how come these hooks and angles to be annexed to this atom? For an atom may be without them; whence comes this union, if such a principle of motion be in each particle? If it be answered, that motion did belong to all these particles, but by degrees the lesser particles hitting together made up these angled and hooked particles; I soon reply, that the difficulty returns more strongly: for if these angled and hooked particles be supposed necessary to the contexture and union of bodies, how came those least imaginable particles ever to unite without such hooks and angles? And so the question will return in infinitum. If then the solidity and indivisibility of these angled atoms doth depend on the union and rest of those lesser imaginable particles joined together, then it is evident that motion is no inseparable property of all these particles, but some are capable of union, in order to the making of such hooks and angles, which are necessary for the contexture of bodies; and where there is union and solidity, there is rest, which is at least accompanied with it, if it be not one of the great causes of it: and without which the atomists, of all other philosophers, will be V. Descar- least able to give an account of firmness in bodies, cip. p. ii. when they make bodies to consist of an aggregation of 56. 'particles; by which it will be very hard finding a suf

tes, Prin

art. 54, 55,

II.

Fluid. and

ficient account of the difference between fluid and firm CHAP. bodies, unless it be from the quicker motion and agitation of the particles of fluid bodies, and the rest of the small and contiguous parts that make up the firm body, according to that catholic law of nature whereby things continue in the state they are in till some stronger force puts them out of it. The only thing which the Epicurean atomists have left to give any account of the solidity of particles of such different sizes, is, the want of vacuity: for, say they, the ground of divisibility of bodies is the interspersion of a disseminated vacuum: now where there is no vacuity, though the particles be of different size, yet they may be solid and indivisible. But this is taken off by the instance History of produced against other persons, by that ingenious and Firm. p. honourable person Mr. Boyle, in his Physiological Es-202. says, which is to this purpose. Suppose two of these presumed indivisible particles, both smooth and of a cubical figure, should happen to lie upon one another, and a third should chance to be fitly placed upon the upper of the two, what should hinder but that this aggregate may, by the violent knock of some other corpuscles, be broken in the midst of the whole concretion, and consequently in the middlemost body? For suppose them as solid as may be, yet since corpuscles as hard as they can be made very violently to knock against them, why may not those grate or break the middlemost corpuscles, or any of the others? And if there be a possibility of breaking off these cubical particles in the middle, then mere want of vacuity is no sufficient account of their being indivisible. By this we see how far the atomists are from giving any rational account of the origin of the motion of the atoms themselves without a Deity.

2. Supposing this motion to be granted them, yet

XVI.

BOOK they cannot give any satisfactory account of the manIII. ner of concretion of bodies, by the casual occursions of these atoms moving in an infinite empty space; which appears from those gross and extravagant suppositions of Epicurus, in order to the making these atoms of his so hit together that they make up any bodies by their

contexture.

1. He supposeth as it were two regions, a superior and inferior, in an infinite empty space, which hath no centre at all in it, nor any body, from which to measure those respects of above and below, as appears by his Epistle to Herodotus, wherein he saith, These terms of ava and Káτw, or upwards and downwards, must be conceived without any bounds or limits at all. So that though we conceive something superior, we must imagine nothing supreme; and so on the conGassend. trary. Whereby it is evident, as Gassendus confesseth, Physic. sect. i. that Epicurus thought the surface of the earth to be a plane, and this plane to be continued up in a level superficies to the heavens, and so to all that immense space of the universe; so that all those heavy bodies which should fall downwards in any parts of the widest distance on the earth, as in Europe, Asia, and Africa, would never meet (if they continued their motion) in the centre of the earth, but would continue their motion still in a parallel line; and so he imagined that which is said to be above as to us, was really the upper part of the world, and so the descent of his atoms must necessarily be downwards towards the earth, according to the weight of them. And was not this a worthy mathematical supposition, for one who would undertake to give an account of the origin of the universe without a Deity?

This motion of descent, by reason of the gravity of atoms, would not serve his turn; for if the atoms

II.

moved downwards thus in a parallel line, how was it CHAP.
possible for them ever to meet for the contexture of
bodies? Now for this purpose he invented a motion of
declination; for finding the motion ad lineam, or ad
perpendiculum as some call it, could not possibly pro-
duce those varieties of bodies which are in the uni-
verse, he supposed therefore the descent not to be in a
perpendicular right line, but to decline a little, that so
several particles, in their descent, might make some
occursions one upon another. And this Epicurus added Cicero de
to Democritus; but therein, as Tully observes, was
very unhappy; that where he adds to Democritus, ea
quæ corrigere vult, mihi quidem depravare videatur ;
that he marred what Democritus had said, by mend-
ing of it. The reason of which motion of declination
is thus given by Lucretius:

Quod nisi declinare solerent, omnia deorsum,
Imbris uti guttæ, caderent per inane profundum;
Nec foret offensus natus, nec plaga creata
Principiis; ita nil unquam natura creasset.

It was obvious to object, that, according to the prin-
ciples of Epicurus, there could have been no concourse
at all of atoms in an infinite space, on the two grounds
he went on; which were the natural descent of atoms,
and the æqui-velocity of the motion of all atoms of
what size soever; which he likewise asserted (although
one would think, if gravity were the cause of motion,
then the more gravity the swifter the motion would
be). From hence, I say, it were not easy to conceive
how the atoms should embrace each other in a parallel
line, if they fell down, as Lucretius expresseth it, like
drops of rain; and therefore they saw a necessity to
make their motion decline a little, that so they might
justle and hit one upon another. But this oblique mo-
tion of the atoms, though it be the only refuge left to

Fin. 1. i.

Lucret. ii.

221.