A most important circumstance in connection with the work of the sixth day is that it witnessed the creation both of man and the mammalia. A fictitious writer would probably have exalted man by assigning to him a separate day, and by placing the whole animal kingdom together in respect to time. He would be all the more likely to do this, if unacquainted, as most ignorant persons as well as literary men are, with the importance and teeming multitudes of the lower tribes of animals, and with the typical identity of the human frame with that of the higher animals. Moses has not done so, we are at liberty to suppose, because the vision of creation had it otherwise; and modern geology has amply vindicated him in this by its disclosure of the intimate connection of the human with the tertiary period; and has shown in this as in other instances that truth and not "accommodation" was the object of the sacred writer. While, as already stated, many existing species extend far back into the tertiary period, showing that the earth has been visited by no universal catastrophe since the first creation of mammals; on the other hand, we can not with certainty trace any existing species back beyond the commencement of the tertiary era. Geology and revelation, therefore, coincide in referring the creation of man to the close of the period in which mammals were introduced and became predominant, and in establishing a marked separation between that period and the preceding one in which the lower animals held undisputed sway. This coincidence, while it strengthens the probability that the creative days were long periods, opposes an almost insurmountable obstacle to every other hypothesis of reconciliation with geological science. At the close of this day the Creator again reviews his work, and pronounces it good. Step by step the world had been evolved from a primeval chaos, through many successive physical changes and long series of organized beings. It had now reached its acme of perfection, and had received its most illustrious tenant, possessing an organism excelling all others in majesty and beauty, and an immaterial soul the shadow of the glorious Creator himself. Well might the angels sing, when the long-protracted work was thus grandly completed: "Thrice happy man, And sons of men, whom God hath thus advanced, Created in his image, there to dwell And worship him, and in reward to rule Over his works in earth, or sea, or air, And multiply a race of worshippers Holy and just; thrice happy, if they know Their happiness and persevere upright."