Throughout the long ages occupied by the depo sition of the mass of sediment of which these bottom rocks are composed, the temperature of the globe must have been very high, though gradually be coming more cool ; and the traces of animal life in them are extremely rare and difficult to detect and identify. The scanty fossil remains which have been discovered by the industry and research of the geologist, reveal no type of animal life of a higher order than the zoophyte (a creature partly of animal and partly of a vegetable nature), annelids or sea worms, and bivalve mollusks—all of them marine creatures devoid of the senses of sight and hearing; and with them have been found traces of fucoids or sea-weeds, but no land vegetation. In fact, all that has been discovered of organic matter in these rocks indicates a beginning of life at the time of their formation, and a beginning of life in the lowest and most humble of its forms.
Now, comparing this picture of the birth and infancy of our planet with the Mosaic description of the first day, or era of the creation, we shall find a remarkabl coincidence between the revela tion and the state of nature which the study of the rocks discloses to have prevailed at this early period of our planet's existence. The earth was without form and void'—unshapen and unfurnished—a conglomeration of gaseous elements, without ani mal or vegetable life within its chaotic precincts ; and such must have been the aspect of our planet in its gaseous state, and when the igneous crust was in process of formation, and in the early stages of the Cambrian system, when it was nothing more than a dark and untenanted watery waste. And the Spirit of God moved on the face of the waters,' or, the life giving spirit of the Creator brooded (for such, according to Gesenius; is the proper transla tion of the Hebrew word ntrm) on the waters, vivifying or impregnating them with life, in the form of those first-born submarine creatures—zoo phytes, annelids, and bivalve mollusks, all of them devoid of the organs of sight, which is some evi dence that, conformably to the Mosaic record, life was on the earth before that light had penetrated to the surface through the encircling vapours which were produced by the central heat acting on and evaporating the waters of the great deep. The rays of the sun had not struggled through the misty zone that was wrapped round the tepid globe ; but, by their gradual refrigeration, the vapours be came less dense and opaque, and when God said, Let there be light,' there was light. Light was
progressive on the face of the earth, lurid and dim; but still it was light, such light as that which visits the earth through a dense fog. Day and night succeeded each other. Evening was and morning was day one (for such is the proper translation of the Hebrew phrase which has been rendered, The evening and the morning were the first day'), though the daylight must, at that early date of its existence, have been of a twilight nature ; and long ages must have, elapsed before that the heat had cooled down sufficiently to permit the orbs of sun, moon, and stars, to become visible to an eye situate at the earth's surface. This will be found to be the true explanation of the phenomenon of the appearance of the heavenly orbs on the fourth day.
The long era of the Cambrian formation was suc ceeded by another as extensive, during which the rocks which have been denominated the Silurian,' were formed, by sedimentary deposits, to the depth of 30,00o feet. The fossil remains of animals throughout this formation are abundant, and dis close the zoology of the era to have been confined to submarine invertebrates. zoophytes, mollusks, and crustaceans ; and no vertebrate animal appears until the close of the era, when the remains of fishes are found in the beds which lie at the top of the Silurian, and just beneath those of the next formation. In the same place, the first traces of land vegetation make their appearance. But the animal and vegetable life of what may he properly termed the Silurian era was marine invertebrate. Light to some extent must have pervaded the earth during this period ; for many of the mollusks, and all of the crustaceans, were furnished with eyes, some of them, as in the instance of the trilobite, of a peculiarly elaborate and perfect structure. It appears to be a law of nature, that animals whose entire existence is passed in darkness, are either wholly devoid of the organs of sight, or, if rudi mentary eyes are discoverable, they are useless for the purposes of vision, as exemplified in the animals of all orders, from the mollusk to the mammals, which have been discovered in the caverns of Illyria, and other caverns of South America, mentioned by Humboldt, in the Mammoth Caves of Ken tucky, in deep wells, and in depths of the sea where no ray of light can penetrate. From this it follows, that the presence of a perfect eye proclaims the presence of light.