CHAPTER III.

THE SCIENTIFIC SYSTEM OF LUCRETIUS.

SECTION I.

THE ANALYSIS OF MATTER.

THE problem Lucretius set himself to solve was a double one. First, What was the original nature of matter? secondly, By what process has it in the course of time arrived at its present state? And the solution he offered was the joint product of certain à priori assumptions and reflections, and a keen and extensive observation of natural facts.

His first great assumption, and his first great observation, were as follows: He assumed that all our knowledge was derived from sense, that the senses were the only channels and the only tests of truth; he observed that the order of things revealed to him by his senses, and whose secrets he had set himself to explain, was something not capricious, but acting in a fixed way, and therefore really constant under all apparent change. "Without fixed seasons of rain,"

he says, "the earth is unable to put forth its gladdening produce; nor, again, if kept from food, could the nature of living things continue its kind and sustain life." "Or again," he asks, "why should not some men outlive many generations, if it were not that an unchanging matter had been assigned for begetting things, and what can arise out of this matter, is fixed?" He observes, further, another set of facts. "Rains die, but goodly crops spring up, and boughs are green with leaves upon the trees. Trees themselves are laden with fruit; by them in turn our race and the race of wild beasts are fed; by them we see glad towns teem with children, and the leafy forests ring on all sides with the song of new birds." And from this Lucretius arrives at another general conclusion. "Nature," he says, "dissolves everything back into its first bodies, and does not annihilate things."

Here, then, he has two broad generalisations to start with. Nature is uniform and nothing in nature can come out of or return to nothing. The first of these conclusions he thinks can stand by itself. He seeks to verify the last one thus: If it be not so -if things can come from nothing-then anything might come out of anything. Men might spring out of the sea, fish out of the earth, birds out of the air. In a word, there could be no such uniformity in the world as there very certainly is. Again, for a like reason, it is plain that nothing can turn into nothing; for in that case objects might suddenly disappear, without any external force destroying them. But this, it is

very certain, they never do. And again, if things could ever turn into nothing, everything would by this time have vanished, "eaten up by the infinite time gone by." And "any amount of force must of course undo the texture of things in which no parts at all were of an everlasting body."

He has thus settled that the universe he has to account for is made up of a matter that, in obedience to fixed laws, is perpetually changing its appearance, and yet is never destroyed. To what is this matter reducible in its last analysis? Lucretius answers, to two things-empty space, and atoms. These atoms are particles of an inconceivable minuteness, and are alike in the absence of all attributes or qualities, except solidity, indestructibility, weight, and figure. They are far too small for sight to take any account of; but this need not make us doubtful of their material reality. We can neither see the wind, or smells, or sounds, or heat, or cold; and "yet," says Lucretius, "all these things must be material, because they touch the senses." Equally necessary, too, is the existence of empty space. For if it were not for this there could be no motion; everything would be a single solid mass. But as a matter of fact we may see that even things that seem solid are not solid really— stones, for instance, through which water often oozes. Further, bodies of equal bulk weigh differently,-from which it is plain that some have more void than others. But though empty space seems thus to enter into everything, there are some bodies that are absolutely solid; and such are the atoms themselves, the first beginnings

of things. For unless these were solid, there would be no matter at all. The universe would be empty space. Equally necessary, too, is it that the atoms should be indivisible; because, Lucretius aptly argues, if Nature had set no limits to the breaking of things, bodies of matter would have been by this time so pulverised that nothing could within a fixed time be conceived out of them, and "reach its utmost growth of being."

Lucretius contrasts this analysis of matter with those of the former speculators, of whom we have already spoken, and shows how inadequate these were to explain the facts of the case. Fire he asks, how can it possibly be true to analyse all things into fire, and say that they were formed out of it? "How," he asks, “can things be so various if they are formed out of fire, one and unmixed? It would avail nothing for hot fire to be condensed and rarefied. The heat would only become more intense by the compression of parts, more faint by their dispersion." No diversity of things could arise in this way; in addition to which, fires can be condensed and rarefied only if there be void, the existence of which those who held that everything was fire necessarily denied. Indeed, says Lucretius, it needs but little exertion of thought to show us that, if we take void away, everything must become solid.x Supposing, however, he goes on, that these philosophers think that fire generates various bodies in some other way, not by condensation and rarefaction. This, for other reasons, is equally impossible. For fire, if it ceases altogether to be fiery, ceases to exist.

Fire, according to the hypothesis now in question, is the essence of all matter-is matter in its simplest state. To say, then, that matter, in this its simplest state, is robbed of all its properties, is just the same as saying that it ceases to exist. And in the majority of things about us there are none of the properties of fire. If, therefore, fire was the primal element, it must have first been turned to nothing; and out of that nothing all these other things must have emerged. "Again," Lucretius goes on, "to say that all things are fire, and no real thing but fire exists, appears sheer dotage. For those who maintain this take their stand on the senses to fight against the senses, which appears to me to be as false as it is foolish. For what surer test can we have than the senses of truth and falsehood? It would be just as wise to deny the reality of fire, and affirm the reality of all other things."

For similar reasons they are wrong who take for a first principle water, or earth, or air; or air and fire; or earth and water together; or, as did Empedocles, fire, water, earth, and air. These speculators were all alike wrong, because they denied the existence of void, and because they supposed matter to be infinitely divisible.

Again, if all things are produced from four things, and again broken up into four things, there is no more meaning in this statement than there would be in its converse-viz., that the various objects and substances about us were the first beginnings of these elements, not these elements the first beginnings of them. Whilst if, to escape this, it be supposed that