There was a time when the earth was an uncomfortable semi-incandescent mass, in the act of cooling off for practical purposes. The atmosphere was tropical throughout the globe. All things were intensely impregnated--or, as the philosophers say, supersaturated--with carbon. Between the dry land and the waters there was no division. There was no ocean, and consequently no continents. All was hot mud, with here and there a lake or a short river, and here and there a dry, parched, torrid eminence. In those days there were animals and plants, but no human beings. Both animals and plants were like the age in which they flourished--to our notions monstrous. Monsters were the rule, both in the vegetable and the animated world. Creatures were born, and grew to sizes which dwarf the elephant. Plants thrust their heads above the mud, and, in that carboniferous atmosphere, attained heights which would have towered above the tallest trees of our forests. But in proportion to the rapidity of their growth was the brevity of their life; for these were the days of earthquakes and terrestrial convulsions. Probably no day elapsed without some earthquake or volcanic eruption. The light of day was dull and obscured. Masses of opaque matter floated through the atmosphere as thickly as dust specks float through a ray of sunlight in a darkened room.[3] The hot air, thick and dull, hung a listless mist over the face of the earth, which was even then almost without form and void. When the sun went down, dense darkness covered the earth. There was no lesser light to rule the night; dim twinklings in the far distance, hardly piercing the pall which wrapped our planet, were the only contrasts to the Egyptian blackness of the dark hours.