Life has had its foetal stage, its stage of infancy, and childhood, and maturity, and will doubtless have its old age. It took it millions upon millions of years to get out of the sea upon dry land; and it took it more millions upon dry land, or since the Carboniferous age, when the air probably first began to be breathable,--all the vast stretch of the Secondary and Tertiary ages,--to get upright and develop a reasoning brain, and reach the estate of man. Step by step, in orderly succession, does creation move. In the rising and in the setting of the sun one may see how nature's great processes steal upon us, silently and unnoticed, yet always in sequence, stage succeeding stage, one thing following from another, the spectacular moment of sunset following inevitably from the quiet, unnoticed sinking of the sun in the west, or the startling flash of his rim above the eastern horizon only the fulfillment of the promise of the dawn. All is development and succession, and man is but the sunrise of the dawn of life in Cambrian or Silurian times, and is linked to that time as one hour of the day is linked to another. The more complex life became, the more rapidly it seems to have developed, till it finally makes rapid strides to reach man. One seems to see Life, like a traveler on the road, going faster and faster as it nears its goal. Those long ages of unicellular life in the old seas, how immense they appear to have been; then how the age of invertebrates dragged on, millions upon millions of years; then the age of fishes; the Palaeozoic age, how vast--put by Haeckel at thirty-four millions of years, adding rock strata forty-one thousand feet thick; then the Mesozoic or third period, the age of reptiles, eleven million years, with strata twelve thousand feet thick. Then came the Caenozoic age, or age of mammals, three million years, with strata thirty-one hundred feet thick. The god of life was getting in a hurry now; man was not far off. A new device, the placenta, was hit upon in this age, and probably the diaphragm and the brain of animals, all greatly enlarged. Finally comes the Anthropozoic or Quaternary age, the age of man, three hundred thousand years, with not much addition to the sedimentary rocks. Man seems to be the net result of it all, of all these vast cycles of Palaeozoic, Mesozoic, and Caenozoic life. He is the one drop finally distilled from the vast weltering sea of lower organic forms. It looks as if it all had to be before he could be--all the delay and waste and struggle and pain--all that long carnival of sea life, all that saturnalia of gigantic forms upon the land and in the air, all that rising and sinking of the continents, and all that shoveling to and fro and mixing of the soils, before the world was ready for him.