perished. Amongst those that were able to propagate themselves, a struggle for existence set in as they increased and multiplied; and in this struggle those animals were eliminated that were not able to defend themselves. "For," says Lucretius, "in the case of all things which go on breathing the breath of life, either craft or courage, or else speed, has from the beginning of its existence protected and preserved each particular race." The only exception is in the case of domestic animals, which, though they may in some ways be weakly themselves, have survived through man's protection.

This theory of the origin of species, it will be seen, is in one of its main features identical with the Darwinian. It attributes exactly the same results to the struggle for existence. But in another point it is entirely and expressly opposed to it. According to the Darwinian theory, all life began in a single simple form, which slowly differentiated itself, through an unexplained tendency of each organism, not only to reproduce its own likeness in its offspring, but also to reproduce this likeness with slight incalculable variations. In this way varieties of organisms kept increasing, all having sprung from the same parent stem, and spreading out into separate branches, which would, if left to themselves, be for ever branching out anew. The rigours of climate, the difficulty of obtaining food, and so on, acted like a force that stripped from such a tree all its weakly twigs, and broke its unsound branches, leaving those only growing that were strong enough to withstand it. In various places this force

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D

varied, and various textures and forms of branches were thus in various places left growing, and destroyed by it. The innate tendency to variation in animals, which the Darwinian theory thus postulates, was conceived of dimly by some of the earliest Greek philosophers, who held that animals only developed legs, and various other parts of their bodies, when the waters dried up that originally covered the earth, and they were thus forced to adapt themselves to a life on land. But all tendency to variation in species is what Lucretius expressly denies. "All living things," he says, "go on after their own fashion, and all preserve their distinctive differences according to a fixed law of nature.” It will thus be seen that the Darwinian theory is an advance on, and differs from, the Lucretian mainly and essentially in this-the way in which the variety is produced which is the subject of the selecting process common to both systems.

SECTION V.

THE NATURE OF LIFE AND CONSCIOUSNESS.

The vital principle, though not identical with the body, is demonstrably itself as truly material as the body. The close connection of the two is a proof of this. For the mind moves the limbs, rouses the body from sleep, and alters the countenance. The mind, too, suffers

with the body. A wound will often cause loss of consciousness, for instance; and that thing must be material which is thus affected by material blows. The vital principle, according to Lucretius, consists of two kinds of ether of surpassing subtlety, diffused through the entire body, and closely connected with each other. Considering how quick are all our thoughts and impulses, the atoms of which these ethers are composed must be perfectly spherical and smooth, and exceedingly small. The entire volume of it must also weigh very little, as after life has left the body, the body does not perceptibly weigh less, any more than wine does when it has lost its flavour or its bouquet.

We are not, however, to suppose that the nature of this ether is single, says Lucretius. It can, on the contrary, be readily analysed into four parts. "For"

so his words run-"a certain subtle spirit mixed with heat quits men at death, and then the heat draws air along with it,—there being no heat which has not air too mixed with it; for since the nature of heat is rare, many first beginnings of air must move about through it." Thus the nature of the vital principle is found to be threefold (i. e., there is the certain subtle spirit,' heat, and air). And yet these things all together are not sufficient to produce sense, since the fact of the case does not admit that any of these can produce sense-giving motions, and the thoughts which a man turns over in his mind. some fourth nature must be added to these. This is altogether without a name. There is nothing exists

Thus

more nimble or more fine, or of smaller or smoother elements. It first transmits the sense-giving motions through the frame,-for it is first stirred, made up as it is of small particles. Next, the heat, and the unseen force of the spirit, receive the motions; then the air; then all things are set in motion, the blood is stirred, and every part of the flesh is filled with sensation.

The mutual connection of these four elements of the vital principle, Lucretius admits that it is very hard to explain. All he says he can do is to illustrate it by an analogy. "As in the flesh of any living creature there is a smell and a heat and a savour, and yet out of these there is made up one single bulk of body, so the heat and the air, and the unseen forces of the spirit, mixed together, produce a single nature, together with that nimble force, which transmits to them from itself the origin of motion, by means of which sense-giving motion first takes its rise through the fleshy frame."

The effects of these various elements are perpetually being visible in the actions and the characters of living things. An angry fire flashes from the eyes in virtue of the elements of heat. Fear is due to the operation of a spirit, which is of a low temperature. A calm cheerfulness is due to a preponderance of the element of still air. Thus passionate animals, such as lions, have in them more of the heat principle. Shuddering, fearful animals, like stags, have more of the chilly principle. Oxen have more of still air. Men have all these elements more equally mixed in them. It is true that they inherit various tendencies

which they cannot utterly eradicate; but the bent given us by our parents is so small, that practically we may overcome it.

Such is the vital principle, and though dwelling in the body and permeating the body, it is not, says Lucretius, as some contend, a mere harmonious working together of the body. For the body is often sick, whilst the mind is enjoying pleasure: often the reverse is the case. Then, too, whilst the body is lying senseless in sleep, our mind is often awake, and is feeling joy and sorrow. Farther, life still stays in the body when many limbs have been lopped off; "and yet the same life, when a few bodies of heat have been dispersed abroad, and some air has been forced out through the mouth, abandons at once the veins, and quits the bones. And thus we see that all bodies do not alike uphold existence, but rather that those seeds which constitute wind and heat cause life to stay in the limbs."

This vital ether, which has been analysed into four constituent elements, from another point of view divides itself into two-viz., the Mind and Soul, which, however, do but "make up a single nature." The mind is the directing principle, and has its seat in the heart. "All the rest of the soul disseminated throughout the body obeys and moves at the beck and movement of the mind.

"The mind has more to do with holding the fast nesses of life, and has more sovereign sway over it, than the power of the soul. For without the understanding and the mind, no part of the soul can maintain itself in the frame for the smallest fraction of