eccentricity until, in time, a regular system would be de veloped, when the whole of the meteorites would travel nearly in the mean plane of their aggregate motions. The larger of the meteorites would tend to settle towards the centre, while other aggregations might easily occur at different distances from the centre. And of these, the outer planets would be larger than the inner ones, because, in the more distant regions, where the attraction of the central sun was less, the movements of the meteorites would be slower, and there would be a greater tendency to agglomeration than where the movements were more rapid. As meteorites contain but little oxygen, hydrogen, carbon, silicon, and alkalies substances which are all abundant on the surface of the earth-large numbers must have been fused together to form the earth, and the lighter substances must have collected near the surface. Consequently, the collisions be

tween these meteorites must have occurred with sufficient rapidity to melt the whole mass. For, after a solid crust had been formed, all the meteorites which fell on the earth would remain on the surface, as they do now.

As with the Solar System, so, also, in the earth itself we can trace distinctly a physical evolution. The discovery of tidal friction gave an independent proof that the earth had had a beginning not infinitely remote, for, if that had been the case, the tidal friction would have reduced the time of the earth's rotation on its axis to that of the moon, Also, we have sufficient geological evidence to show that not more than one hundred millions of years ago the earth was in a molten condition, and, probably, shone with its own light. As cooling went on, the silicates crystallised out, forming a solid crust over the still molten, metallic interior, and the earth then became a dark body. At that time, all the water above the crust was in a state of vapour, which, subsequently, fell as hot rain, forming a boiling ocean. With this rain the denudation of the primitive crystalline rocks commenced, and their débris was deposited on the bed of the ocean as sedimentary rocks. Gradually, the continents were formed, the new ranges of mountains following each other in orderly succession, the great oceans becoming narrower and deeper, as well as more and more salt. These processes are still going on, but, as the earth is cooling, the internal energy which uplifts the mountains must be diminishing, and, in time, it will be insufficient to counteract the denudation. Then the whole of the land will be swept into the sea, and the waves of the ocean will roll over the surface of the earth unopposed. Unless, indeed, before that time arrives, the ocean should have been frozen into a mass of ice,

or should have sunk slowly into the ground. All these things are approaching, but which of them will come first it is impossible to say.

ORGANIC EVOLUTION.

These in

When, during the course of physical evolution, the ocean had become sufficiently cool for the existence of protoplasm, minute living organisms appeared on its surface. creased in size, varied in many directions, and, in time, dis covered the bottom of the sea, on which they established themselves, changing from swimming to crawling creatures. Gradually, these organisms managed to live in safety among the rough waters of the sea coast, and then they spread over the land. First the plants, and then the animals, which came to feed on the plants.

Once established on land, and breathing air, improve ments in the circulatory system of the higher animals became possible. The purified blood was kept separated from the impure blood, and increased rapidity of physiological processes heated the body, so that, in the birds and mammals, a stream of pure, warm blood was poured upon the brain. Thus stimulated, the brain developed rapidly, and the psychological evolution, thus inaugurated, has reached such a height in man as to place him mentally apart from the rest of the animal kingdom.

Biological evolution differs from physical evolution in being brought about by the transmission of bodily variations from one generation to another. And, in psychological evolution, mind is transmitted from parent to offspring, as well as the organ in which it is to be manifested. gence, however, depends not only on the structure of this organ, but on early associations and education, by which means the wisdom of one generation is handed down to the

next.

Intelli

Psychological evolution consists of two parts. The first is intellectual, and is found in all the higher animals, as well as in man. The second is ethical, and is exclusively human.

Intellectual evolution, like biological evolution, is due to competition between different individuals and the action of selection. We probably see the first germs of ethical evolution in parental affection, which, among gregarious animals of sufficient intelligence, widened into social sympathy, and this, in man, gave rise to the social or civic virtues.

This advance also appears to have been, or, at any rate, may have been, due to selection, and the result was the

emergence of what is called utilitarian morality. Morality, in the strict sense of the term—that is, formal morality— also appears to have arisen from sympathy, but not by means of selection. The long and constant use by man of formal morality has made it instinctive, and has thus given rise to the conscience.

How sympathy gave rise to the conscience is a difficult problem, about which we know very little at present, for few people have taken up the study of ethics from an observational basis. Darwin asks: Why does man regret, even though trying to banish such regret, that he has followed a natural impulse rather than a higher ideal; and why does he further feel that he ought to regret his conduct, while such a course never occurs to animals? And he answers:

It is because the higher impulse, due to sympathy, is continuous; while the lower one, due to selfishness, is temporary. And, comparing the transient impressions of past indulgence with the ever-present feeling of sympathy, he feels that he was mistaken in following the lower impulse. And it is this that causes him regret, or even shame.*

But the process, as described by Darwin, evidently implies a considerable intellectual capacity, and, what is still more important, the exercise of free will. For no one could regret following a lower impulse unless he felt that he had the power to choose a higher one. Ethical development. therefore, could only commence at a stage far above the highest apes, and, probably, above the earlier forms of man. Meantime, while this growth of sympathy was taking place, the evolution of religion, as already described, would have been going on, and the priest would have assumed a position of great importance. It is he who would draw up the standard of right and wrong, and thus morality would be reinforced, and stimulated by the religious feeling.

It, therefore, appears that ethical and religious development were at first separate, but quickly coalesced, until, in Christian countries, they are completely blended. But this mutual dependence is not so pronounced everywhere. The Chinese and Japanese have high codes of morals with very indistinct notions of religion; while the Hindus have very strong religious feelings, combined with weak ideas of morality. However, it is not possible to give even the slightest outline of ethical evolution without mentioning the religious element. The important point to remember is that ethical development is due to a conflict of wishes in the individual himself, and is possible only because man has the

Descent of Man, 2nd. ed., page 112.

power of choosing one of these wishes, and acting upon it; that is, to the exercise of free will. It seems to me that free will would be useless to any being who did not possess a moral sense, for its only use is to cultivate morality. The exercise of this free will by ignorant man leads to much injustice on the earth; but that is part of his education, and no doubt the end will be found to justify the means.

Now, we cannot think that the evolutionary process, of which I have given you a mere sketch, is confined to the earth alone. We must suppose that, whatever may be the object for which the Solar System was called into existence, it is for the same purpose that the various stellar systems exist. And, in all probability, long after the sun is cold and dark, other stellar systems, each in its turn, will take up the development of life and mind. But they, also, in time. will become cold and lifeless, until, at last, the process, so far as it is connected with the material Universe, will be But is it not possible that evolution may still go on after life has perished? This is a point to which I will return presently.

over.

DESIGN IN NATURE.

Evolution is evidently due to the action of mind. There are some who still maintain an opposite view, but I think that their numbers are fast diminishing. It seems to me that no one who has a competent knowledge of biology and palæontology can possibly accept the doctrine that living organisms are the outcome of chance. Darwin distinctly repudiated the idea, and thought that variation in animals and plants could not be explained by a mechanical theory of the Universe. I must here try to make my meaning clear. We apply the word chance to those phenomena which are irregular in their appearance, and which are due to causes too complicated for us to unravel. We call throwing dice chance, because we cannot foretell what will happen. Similarly, if we say that evolution is due to chance, we mean that the Author of Nature could not foretell the results of the action of the forces he was setting in motion. Now, is the universe due to design, or is it due to what we may call a lucky throw ? Has it been brought about intentionally or unintentionally? That is the question.

It may be possible to imagine a cloud formed by meteorites, which are moving rapidly in all directions, but are unable to escape from the cloud, gradually changing, by mechanical laws, into a sun with its attendant planets. But we cannot imagine how the action of any mechanical causes could clothe one of those planets with vegetation; fill that vegetation with various kinds of animal life, and, at last.

give rise to a being with sufficient intelligence to ask how and why it was all done. The idea that physical forces called into existence indiscriminately, and without any ulterior object, could, by their interaction, evolve the earth and all that is on it, is, evidently, quite incredible. But this general statement leaves only a vague impression on the mind, and, in order to clear our ideas, I will give you two examples, one taken from inorganic, the other from organic, nature, and treat them in some detail.

In the first place, let us consider the formation of the earth itself. It is evident that no organic development of importance can ever take place on the sun; for, when it has cooled sufficiently to make the formation of protoplasm possible, the temperature of its surface will be rapidly reduced to a point below which protoplasm could not live, so that there would be no time for life to develop. From this we

learn that biological evolution can only proceed on a cool body, the surface temperature of which is kept nearly equable by radiation from another hot body. As these conditions must last for a long time, the hot body must be large, and at a proper distance from the cool body. But much more than this is required for the development of life. If living organisms were intended to progress from the ocean to the land, in the way I have already mentioned, provision must be made for the continuous existence of land from the close of the Cambrian period, and this land must be well watered. Consequently, the surface of the earth must consist partly of land and partly of water, in due proportion; and the actual amount of water necessary will depend upon the size of the earth. The rain, falling on the land, constantly washes it down into the sea, and some agency must exist for renewing the land by elevation. This eleva tion depends upon the mobility of the crust, which again depends upon the internal temperature of the earth. This. therefore, it is necessary to conserve. Again, the mass of the earth must be sufficiently great to retain on its surface by gravitation the water-vapour, which would fly off and leave the world dry if the mass was too small. And, once more, the materials necessary for supporting life and building up organisms must be present.

From these considerations, it follows that, to secure a long development of life, the mass of the earth must be considerable, and that the cooled crust must be a bad conductor of heat. That is, it must be formed of oxides, and not of unoxidised metals. There must also be a certain relationship between the quantities of the several elementary substances of which organisms are composed.

It is necessary