Besides the want of a fixed era, and the insufficient knowledge of the ancient period, and of the alien monarchy--besides the motives of national vanity, there was another remarkable circumstance connected with the priests of Egypt which was calculated to lead them far away from historical truth. The Egyptians measured time by a solar year of 360 days, divided into twelve months of thirty days. It was early observed that this year did not correspond to the sun's orbit; and therefore five additional days were added. The decisive event of the Egyptian year was the inundation. The Nile began to rise at the time of the summer solstice, and was coincident with the rising of the Dog-star (Sothis), the brightest star in the Egyptian sky. The Dog-star proclaimed the approach of the inundation and the new fertilization of the soil, and by proclaiming caused it. Thus to the Egyptians this star Sothis was "the Lady of the Beginning." The rising of the star denoted the new year; which therefore must have begun on the 20th July, the first of Thoth in the Egyptian calendar. But since, in the Egyptian year, a quarter of a day was wanting, in spite of the additional five years, to make up the true astronomical year, the beginning of every fourth year must have been a day in advance of the true year, and the seasons, of which the Egyptians made three of four months each, the months, and the festivals anticipated more and more the true time of the year. This advance could not have escaped the priests; they must soon have observed that a period of 1,461 Egyptian years must elapse in order to allow the Egyptian year to coincide with astronomical time. For in 1,460 Egyptian years the additional quarter of a day in the astronomical year would amount to 365 whole days--_i.e._ to an Egyptian year; and at the end of this year the beginning of the next was again coincident with the rising of the Dog-star, as seen from Lower Egypt, and the commencement of the inundation. Thus in a period of 1,461 years the year was again brought to its true beginning.[28] Since the fruitfulness and life of the Egyptian land depended on the inundation, and the inundation began with the rising of the Dog-star, the history of Egypt must also have begun with a similar rising. If after 1,461 Egyptian years the rising of the Dog-star again coincided with the beginning of the civic year, the priests would regard this restoration of the natural order as the completion of a great cycle of events. The Dog-star brought the inundation, and with it the fruits and life of Egypt. It was the awakener of life. It must therefore have brought life to the world also; time must have begun with the rising of Sirius. Porphyrius tells us that to the Egyptians the rising of the Dog-star was the beginning of the world.[29] Hence the periods of the world must proceed according to a number of periods fixed by the Dog-star. It seems that the priests