begin? When did each stage of our mental growth begin? When or where did the English language begin, or the French, or the German? Was there a first English word spoken? From the first animal sound, if we can conceive of such, up to the human speech of to-day, there is an infinite gradation of sounds and words.

Was there a first summer, a first winter, a first spring? There could hardly have been a first day even for ages and ages, but only slowly approximating day. After an immense lapse of time the air must have cleared and the day become separated from the night, and the seasons must have become gradually defined. Things slowly emerge one after another from a dim, nebulous condition, both in our own growth and experience and in the development of the physical universe.

In nature there is no first and last. There is an endless beginning and an endless ending. There was no first man or first woman, no first bird, or fish, or reptile. Back of each one stretches an endless chain of approximating men and birds and reptiles.

This talk about the time and place where man began his existence seems to me misleading, because it appears to convey the idea that he began as man at some time, in some place. Whereas he grew. He began where and when the first cell appeared, and he has been on the road ever since. There is no point in the line where he emerged from the not-man and became man. He was emerging from the not-man for millions of years, and when you put your finger on an animal form and say, This is man, you must go back through whole geologic periods before you reach the not-man. If Darwin is right, there is no more reason for believing that the different species or forms of animal life were suddenly introduced than there is for believing that the soil, or the minerals, gold, silver, diamonds, or vegetable mold and verdure were suddenly introduced.

II

If we know anything of the earth's past history, we know that the continents were long in forming, that they passed through many vicissitudes of heat and cold, of fire and flood, of upheaval and subsidence--that they had, so to speak, their first low, simple rudimentary or invertebrate life, that they were all slow in getting their backbones, slower still in clothing their rock ribs with soil and verdure, that they passed through a sort of amphibian stage, now under water, now on dry land, that their many kinds of soils and climes were not differentiated and their complex water-systems established till well into Tertiary times--in short, that they have passed more and more from the simple to the complex, from the disorganized to the organized. When man comes to draw his sustenance from their breasts, may they not be said to have reached the mammalian stage?

The fertile plain and valley and the rounded hill are of slow growth, immensely slow. But any given stage of the earth has followed naturally from the previous stage, only more and more and higher and higher forces took a hand in the game. First its elements passed through the stage of fire, then through the stage of water, then merged into the stage of air. More and more the aerial elements--oxygen, carbon, nitrogen--have entered into its constituents and fattened the soil. The humanizing of the earth has been largely a process of oxidation. More than disintegrated rock makes up the soil; the air and the rains and the snows have all contributed a share.

The history of the soil which we turn with our spade, and stamp with our shoes, covers millions upon millions of years. It is the ashes of the mountains, the leavings of untold generations of animal and vegetable life. It came out of the sea, it drifted from the heavens; it flowed out from the fiery heart of the globe; it has been worked over and over by frost and flood, blown by winds, shoveled by ice, --mixed and kneaded and moulded as the house-wife kneads and moulds her bread,--refining and refining from age to age. Much of it was held in solution in the primordial seas, whence it was filtered and used and precipitated by countless forms of marine life, making a sediment that in time became rocks, that again in time became continents or parts of them, which the aerial forces reduced to soil. Indeed, the soil itself is an evolution, as much so as the life upon it.

We probably have little conception of how intimate and cooperative all parts of the universe are with one another,--of the debt we owe to the farthest stars, and to the remotest period of time. We must owe a debt to the monsters of Mesozoic and Caenozoic time; they helped to fertilize the soil for us, and to discipline the ruder forces of life. We owe a debt to all that has gone before: to the heavens above and to the earth-fires beneath, to the ice-sheets that ground down the mountains, and to the ocean currents. Just as we owe a debt to the men and women in our line of descent, so we owe a debt to the ruder primordial forces that shaped the planet to our use, and took a hand in the game of animal life.

The gods of evolution had served a long apprenticeship; they had gained proficiency and were master workmen. Or shall we say that the elements of life had become more plastic and adaptable, or that the life fund had accumulated, so to speak? Had the vast succession of living beings, the long experience in organization, at last made the problem of the origin of man easier to solve?

One fancies every living thing as not only returning its mineral elements to the soil, but as in some subtle way leaving its vital forces also, and thus contributing to the impalpable, invisible store-house of vital energy of the globe.

At first among the mammalian tribes there was much muscle and little brains. But in the middle Tertiary the mammal brain began suddenly to enlarge, so that in our time the brain of the horse is more than eight times the size of the brain of his progenitor, the dinoceras of Eocene times.

Nature seems to have experimented with brains and nerve ganglia, as she has with so many other things. The huge reptilian creatures of Mesozoic time--the various dinosaurs--had ridiculously small heads and brains, but they had what might be called supplementary brains well toward the other end of the body,--great nervous masses near the sacrum, many times the size of the ostensible brain, which no doubt performed certain brain functions. But the principle of centralization was at work, and when in later time we reach the higher mammalian forms, we find these outlying nervous masses called in, so to speak, and concentrated in the head.

Nature has tried the big, the gigantic, over and over, and then abandoned it. In Carboniferous times there was a gigantic dragon-fly, measuring more than two feet in the expanse of wings. Still earlier, there were gigantic mollusks and sea scorpions, a cephalopod larger than a man; then gigantic fishes and amphibians and reptiles, followed by enormous mammals. But the geologic record shows that these huge forms did not continue. The mollusks that last unchanged through millions of years are the clam and the oyster of our day. The huge mosses and tree-ferns are gone, and only their humbler types remain. Among men giants are short-lived.

On the other hand, the steady increase in size of certain other species of animals during the later geologic ages is a curious and interesting fact. The first progenitors of the elephant that have been found show a small animal that steadily grew through the ages till the animal as we now find it is reached. Among the invertebrates this same progressive increase in size has been noted, a small shell in the Devonian becoming enormous in the Triassic. Certain species of sharks of medium size in the lower Eocene continue to increase till they attain the astounding dimensions in the Miocene and Pliocene of over one hundred feet long. A certain fish appearing in the Devonian as a small fish of seven centimetres in length, becomes in the Carboniferous era a creature twenty-seven centimetres in length. Among the mammals of Tertiary times this same law of steady increase in size has been operative, as seen in the Felidae, the stag, and the antelope. Man himself has, no doubt, been under the same law, and is probably a much larger animal than any of his Tertiary ancestors. In the vegetable world this process, in many cases, at least, has been reversed, and the huge treelike club-mosses and horsetails of Carboniferous times have dwindled in our time to very insignificant herbaceous forms.

Animals of overweening size are handicapped in many ways, so that nature in most cases finally abandons the gigantic and sticks to the medium and the small.

III

Can we fail to see the significance of the order in which life has appeared upon the globe--the ascending series from the simple to the more and more complex? Can we doubt that each series is the outcome of the one below it--that there is a logical sequence from the protozoa up through the invertebrates, the vertebrates, to man? Is it not like all that we know of the method of nature? Could we substitute the life of one period for that of another without doing obvious violence to the logic of nature? Is there no fundamental reason for the gradation we behold?

All animal life lowest in organization is earliest in time, and vice versa, the different classes of a sub-kingdom, and the different orders of a class, succeeding one another, as Cope says, in the relative order of their zoological rank. Thus the sponges are later than the protozoa, the corals succeed the sponges, the sea-urchins come after the corals, the shell-fish follow the sea-urchins, the articulates are later than the shell-fish, the vertebrates are later than the articulates. Among the former, the amphibian follows the fish, the reptile follows the amphibian, the mammal follows the reptile, and non-placental mammals are followed by the placental.

It almost seems as if nature hesitated whether to produce the mammal from the reptile or from the amphibian, as the mammal bears marks of both in its anatomy, and which was the parent stem is still a question.

The heart started as a simple tube in the Leptocardii; it divides itself into two cavities in the fishes, into three in the reptiles, and into four in the birds and mammals. So the ossification of the vertebral column takes place progressively, from the Silurian to the middle Jurassic.

The same ascending series of creation as a whole is repeated in the