The study of the trilobites naturally leads to the consideration of those beings which appear to have inhabited our earth previous to the creation of man. Every one knows that the sceptical naturalist has drawn from these vestiges of organic life, an argument contradictory to the Mosaic account of the history of the world, and though every cavil of the least importance, urged against the truth of the sacred historian, has been triumphantly confuted, still, the geological sciolist boldly impugns his veracity, whenever any new facts in his science can be distorted to his purpose. Such being the case, we cannot conclude this preface without briefly stating two or three methods by which any seeming discrepancies may be explained. First, those who imagine that the six periods of creation, mentioned in the beginning of the pentateuch, mean literally days of 24 hours each, believe that, as only a small part of the earth was at first required for the abode of man and the higher animals, the present continents might have remained as long beneath the waters, and have undergone every change necessary to solve this geological puzzle. Again, others have thought that Moses, after recording, in the first sentence of Genesis, the great truth that all things were made by the will of an intelligent Creator--passed silently over some intermediate state of the earth, which had no direct relation to the history, or to the duties of man--and proceeded to describe the successive appearance of the present order of things. On this supposition, the fossil remains and peculiarities in the structure of the earth may have belonged to that intermediate state. A third method of explaining the difficulty, and which we think highly satisfactory, is, by understanding the days of creation to mean, not ordinary days, but _periods of time_, in which the recorded events took place in the order described so briefly by the sacred historian. It is acknowledged by every one competent to judge, that among the Hebrews, _days_ and _weeks_ were often used in this manner. The accordance between the order in which, according to the account of Moses, the work of creation was accomplished, and the order in which the fossil remains of plants and animals are deposited in the earth, has surprised, and has been acknowledged by learned sceptics themselves.[11] [Footnote 11: The Baron Cuvier, on this subject, remarks, respecting the Jewish legislator--"His books show us, that he had very perfect ideas respecting several of the highest questions of natural philosophy. His cosmogony, especially, considered purely in a scientific point of view, is extremely remarkable, inasmuch as the order which it assigns to the different epochs of creation, is precisely the same as that which has been deduced from geological considerations."]