(M22) Thus the official calendar was completely divorced, except at rare and long intervals, from what may be called the natural calendar of the shepherd, the husbandman, and the sailor—that is, from the course of the seasons in which the times for the various labours of cattle-breeding, tillage, and navigation are marked by the position of the sun in the sky, the rising or setting of the stars, the fall of rain, the growth of pasture, the ripening of the corn, the blowing of certain winds, and so forth. Nowhere, perhaps, are the events of this natural calendar better marked or more regular in their recurrence than in Egypt; nowhere accordingly could their divergence from the corresponding dates of the official calendar be more readily observed. The divergence certainly did not escape the notice of the Egyptians themselves, and some of them apparently attempted successfully to correct it. Thus we are told that the Theban priests, who particularly excelled in astronomy, were acquainted with the true length of the solar year, and harmonized the calendar with it by intercalating a day every few, probably every four, years.(49) But this scientific improvement was too deeply opposed to the religious conservatism of the Egyptian nature to win general acceptance. “The Egyptians,” said Geminus, a Greek astronomer writing about 77 B.C., “are of an opposite opinion and purpose from the Greeks. For they neither reckon the years by the sun nor the months and days by the moon, but they observe a peculiar system of their own. They wish, in fact, that the sacrifices should not always be offered to the gods at the same time of the year, but that they should pass through all the seasons of the year, so that the summer festival should in time be celebrated in winter, in autumn, and in spring. For that purpose they employ a year of three hundred and sixty-five days, composed of twelve months of thirty days each, with five supplementary days added. But they do not add the quarter of a day for the reason I have given—namely, in order that their festivals may revolve.”(50) So attached, indeed, were the Egyptians to their old calendar, that the kings at their consecration were led by the priest of Isis at Memphis into the holy of holies, and there made to swear that they would maintain the year of three hundred and sixty-five days without intercalation.(51)