123. Fourth. Bodies are either first beginnings of things (atoms), or a union of such. Any thing which can be broken or crushed, or which can transmit heat or electricity, is partly body and partly void. Hence body cannot be crushed, and ‘therefore first beginnings are of solid singleness, and in no other way can they have been preserved through ages during infinite time past, in order to reproduce things.’
124. Fifth. If there be no limit to breakage, nothing could be reproduced; for reproduction is slower than decay, and therefore the breaking of infinite past ages would have produced a state of things incompatible with the reproduction of anything within finite time. Hence there exists a least in things. This cannot be soft, else it would consist partly of void, and be therefore breakable.
First beginnings, then, are strong in solid singleness. Hence the unreason of those who held fire to be the matter of things, for what surer test can we have than the senses whereby to note truth and falsehood!
The doctrine called that of Homœomeria by Anaxagoras is folly,—his notion, to wit, that everything is made up of little parts the same as itself—bones of little bones, flesh of little fleshes, etc. For thus corn and other food, which go to nourish our blood, must be in part composed of blood, and must therefore bleed when crushed by the formidable force of the millstone!
125. Sixth. Are the atoms infinite in number, and is the void in which they move unlimited? Both questions are answered in the affirmative, but the proof given is metaphysical and altogether ridiculous, though it contains a fragmentary passage of real merit, hinting at Le Sage’s explanation (presently to be given) of the cause of gravity. One illustration of it must suffice:—‘Nature keeps the sum of things from setting any limit to itself, since she compels body to be ended by void, and void in turn by body;’ so that either by the alternation of the two, or by the infinite extension of one if the other do not bound it, immeasurable space must be filled. If, for instance, body were finite, and void infinite, matter would in a very short time be scattered and borne along in the mighty void; or, rather, could never have been brought together.
This agrees with an idea which is propounded in the second book, as to the velocity which the atoms have given them (he does not say how or whence), and which enables them to cohere for a time and then to break up again, as everything wanes. Those whose close-tangled shapes hold them fast together form enduring stone and unyielding iron, others spring far off and rebound, leaving great spaces between; ‘these furnish us with thin air and bright sunlight.’ Shortly afterwards, we are told that the velocity of the first beginnings when passing through empty void must be greater than that of sunlight!
We need not trouble ourselves here with Lucretius’s speculations as to the formation of tangible bodies from a vertical downpour of atoms, which, unlike drops of rain, now and then swerve from their courses so as to clash together, save to mention that he affirms that, even if he did not know what atoms are, he could be sure, from its defects, that the world was not made for us by divine power.
126. Seventh. This, one of the most important points of the whole theory, is entirely ignored by some good commentators, and by others who have more or less closely followed them:—The first beginnings of things have different shapes, but the number of shapes is finite.
127. Eighth. The first beginnings which have a like shape, one with another, are infinite in number.
That is, there is a finite number of kinds of atoms, but an infinite number of each kind.