Thus, when we have come to look upon life and nature in the light of evolution, what vistas are opened to us where before were only blank walls! The geologic ages take on a new interest to us. We know that in some form we were even there. The systems of sedimentary rocks which the geologist portrays, piled one upon the other to a depth of fifty miles or more, seem like the stairway by which we have ascended, taking on some new and more developed form at each rise. What we were at the first step in Cambrian times only the Lord knows, but whatever we were, we crept up or floated up to the next rise. In the Silurian seas we may have been a trilobite for aught we know; at any rate, we were the outcome of the life impulse that begat the trilobites, but our fate was not bound up with theirs, as their race came to an end in those early geologic ages, and our stem form did not. Whether or not we were a fish in the Devonian seas, there is little doubt that we had gills, because we have the gill slits yet in our early foetal life, and it is quite certain that in some way we owe our backbones to the fishes. When the rocks that form my native Catskills were being laid down in the Devonian waters, I fancy that my aquatic embryo was swimming about somewhere and slowly waxing strong. Up and up I climbed across the sandstone steps, across the limestone, the conglomerate, the slate, up into Carboniferous times. The upper and nether millstones of the "millstone grit" did not crush me, neither did the floods and the convulsions of Carboniferous times that buried the vast vegetable growths that resulted in our coal measures engulf or destroy me. About that time probably, I emerged from the water and became an amphibian, and maybe got my five fingers and five toes on each side. Nor did the wholesale destruction of animal life at the end of Palaeozoic time cut off my line of descent. The monstrous reptiles of the succeeding or Mesozoic age, the petrified remains of one of which was recently found in the sandstone rocks near the river's edge under the Palisades of the Hudson, do not seem to have endangered the golden thread by which our fate hung. Still "I mount and mount." The stairs by which I climb were rent by earthquakes and volcanoes, the strata were squeezed up and overturned and folded in the great mountain-chains; the Alps, the Andes, the Himalayas, the Coast Range were born; the earth-throes must have been tremendous at times; yet I escaped it all. The huge and fearful mammals of the third or Tertiary period passed me by unharmed. Eruptions and cataclysms, the sinking of the land, the inundations of the sea, world-wide deformations of the earth's crust, fire and ice and floods, monsters of the deep and dragons of the land and the air have beset my course from the first, and yet here I am, here we all are, and apparently none the worse for the appalling dangers we have passed through.