Leaving the Aryan stream, and turning back to that division of the great Iranian family which migrated to the valley of the Nile, and which we call the Egyptian, we find a very similar religious system in vogue among them from the very earliest times, as existed among the Aryans. The first settlers in Egypt carried with them, no doubt, the primitive religious conceptions of their Iranian fathers, which were derived from a contemplation of the various phenomena of nature, as previously stated; and it is highly probable that, at a very early period, they gave considerable attention to the movements of the heavenly bodies, for from monumental inscriptions, unearthed in modern times, which geologists inform us must have lain _sub terra_ for several thousands of years, we learn that the Egyptians, at that remote time, well understood the theory of the precession of the equinoxes, placing the zodiacal constellation of the bull at the vernal equinoxial point in the period prior to about B.C. 4300, and that of the ram in the period immediately following. It is probable, therefore, that hundreds of years before this time these primitive men of the Nile were engaging themselves with the study of astronomy, and using effective astronomical instruments, which indicates a high state of civilisation; and this is further borne out by the fact that, at the commencement of the first Egyptian dynasty, about the year B.C. 5000, when Menes reigned over Egypt, there was every appearance of a very advanced civilisation that had lasted for centuries. From the “Book of the Dead” and the Prisse Papyrus (most of the former written at latest prior to B.C. 4000, and the latter very soon after) we derive a tolerably accurate notion of the mythological system of the Egyptians during the first portion of the Old Empire, and probably many hundreds of years previously; while, from the writings of Herodotus, Diodorus, Plutarch, and Manetho, we learn the progress the religion made during the 4,000 following years.