These three temples of Edfou, Dendera, and Esné, to which some others in Upper Egypt may be added, are of great value historically. They enable us to understand what was the condition of Egyptian art, and, to some extent, in what condition the Egyptians themselves were in the Greek, and in the Roman period. From the time of Menes to the time of Decius we see that they possessed the same language, the same arts, the same style of art, the same method of writing, the same mythology, and the same social arrangements. The mind is almost overwhelmed at the contemplation of such stability in human affairs. With this vast tract of time, spread over four thousand years, we are acquainted historically. Of the period that preceded it we have no monuments, and know nothing historically. What we know, however, of the historical period enables us to infer with confidence that the period which preceded it, and in which all this knowledge, all these arts, and these aptitudes were acquired, this mythology constructed, and this social organization, possessing so much vitality and permanence, grew into form, and established itself, could not possibly have been a short period. The antiquity of the sites of Dendera and Esné, and perhaps also of Edfou, must have contributed largely towards the eventual preservation of their temples. When a temple had for some thousands of years been standing on the same site, the surrounding city necessarily rose very much above it. This rise would be more rapid in Upper Egypt than in the Delta from merely natural causes, for the yearly deposit of soil is far greater in that part of the valley which first receives the then heavily mud-charged waters of the inundation. When, therefore, these cities were overthrown or deserted, the deep depressions, in which the temples stood, were soon filled from the rubbish of the closely surrounding mounds; and the temples, thus buried, were preserved. Both at Dendera and Esné the very roofs are below the level of the mounds, and nothing can be seen till excavations have been made, in which the temples are found complete. It was almost the same at Edfou also.