Observations on the sun's annual course led to the fixing of it along a zodiac of twelve signs, corresponding roughly to twelve lunar months, and defined by constellations, or groups of stars, having a fanciful resemblance to animals or deified heroes. Those zodiacal signs are of immense antiquity and world-wide universality. We find them in the earliest mythology of Chaldæa and Egypt, in the labours of Hercules, in the traditions of a deluge associated with the sign of Aquarius, and even, though in a somewhat altered form, in such distant countries as China and Mexico. Probably they originated in Chaldæa, where the oldest records and universal tradition show the primitive Accadians to have been astronomers, who from time immemorial had made observations on the heavenly bodies, and who remained down to the Roman Empire the most celebrated astrologers, though it is not quite clear whether Egyptian astronomy and astrology were imported from Chaldæa or invented independently at an equally remote period. Even if we admit, however, Procter's suggestion that the pyramids had an astrological origin in addition to their primary object as tombs, it is difficult to understand how such enormous structures could have been built. The Great Pyramid must have been built on a plan designed from the first, and not by any haphazard process of adding a layer each year according to the number of years the monarch happened to reign. How could he foresee the exact number of years of an unusually long life and reign, or what security could he have that, if he died early, his successor would complete his pyramid in addition to erecting one of almost equal magnitude for himself? How could three successive kings have devoted such an amount of the nation's capital and resources to the building of three such pyramids as those of Cheops, Chephren, and Mycerinus, without provoking insurrections? Herodotus has a piece of gossip, probably picked up from some ignorant guides, which represents Cheops and Chephren as detested tyrants, who shut up the temples of the gods, and confounds the national hatred of the shepherd kings, who conquered Egypt some 2000 years later, with that of these pyramid-builders; but this is confuted by the monuments, which show them as pious builders or restorers of temples of the national gods in other localities, as for instance at Bubastis, where the cartouche of Chephren was lately found by M. Naville on an addition to the Temple of Isis. All the records also of the fourth or pyramid-building dynasty, and of the two next dynasties, show it to have been a period of peace and prosperity.