20. The mysterious character of the river seems to have deeply impressed the nation with awe and reverence for unseen powers, and contributed to the influence of the priestly caste. Their peculiar source of wealth and the amount of leisure periodically afforded, perhaps led to the construction of the temples and palaces, whose gloomy strength is as mysterious as their river, or the origin of the people. Far back in the twilight of time, Thebes, the “city of a hundred gates,” was a colossal capital. Its vast temples and palaces were built on a scale of grandeur that seems almost superhuman; yet, before history begins its narrative in Greece, Thebes had had its youth, its long period of splendor and glory, its hoary age, and was already a thing of the past, and nearly in ruins; not by violence or conquest, but by the natural transfer of the center of activities to another region. Considering the small extent of Egypt, its always overflowing population, and the tenacious habits of the Egyptians, nothing could more impressively show its great age. 21. Egyptian sculpture was descriptive of religious ceremonies on the temples, and on the palaces of domestic life and general habits, and furnishes us with details of the whole social structure and all their industrial pursuits, as well as the events in the campaigns of their few warlike monarchs. Add to these the minute delineation of their temple service and religious teachings, and its ruins describe the entire round of its ancient life. The people were divided into classes, or castes, the son being obliged to follow the occupation of the father; and all branches of business and industry, public and private, were arranged in the most methodical manner. The priest, the soldier, the husbandman, the artisan of whatever branch, was so because his ancestors had been such for numberless generations. A king could be selected either from the priestly or the soldier caste; but he must previously have been initiated into all the mysteries of the priesthood, and therefore Moses, the acknowledged heir of the throne, “was learned in all the wisdom of the Egyptians.” Otherwise, not belonging to the priestly caste, he must have remained in ignorance. With this exception, the priest alone had the key of knowledge, and all the employments requiring intellectual studies, or scientific culture, as we should now say, were filled from that class. They kept all records, measurements, and apportionments of land; prescribed the times, seasons, and conduct of all public transactions; were the constitutional advisers of the king; they were physicians, astronomers, philosophers, and guides of the people in every respect. They alone did the thinking, and they guarded their prerogative with the most jealous care.