The Diurnal Events
First we have to reckon with the diurnal events. At daybreak and nightfall the shepherd, as he stands at the door of his hut, sees the sun rising in different positions at different times of the year, but always towards one side of the horizon. He watches it, as it sets in different positions at different times of the year, but always towards the opposite side of the horizon. So he learns to distinguish an eastern horizon of sunrise and a western horizon of sunset. In the region north of the tropics, where the neolithic agrarian economy began, the sun travels over the heavens obliquely, so that the noon shadow is always on one side of the line joining the eastern and western horizons. The sun's shadow shortens as day wears on till the sun itself is highest in the heavens, and then lengthens again as it points more and more towards the place of the rising sun. The noon or shortest shadow divided the working day of the cultivator into morning and afternoon. Fisher folk would be familiar with other time signals besides the daily changes of the sun and stars. They would see how high and low water at the tide marks would happen twice in a day and a night. Before there was any settled husbandry, hunting and food-gathering tribes had learned to recognize familiar star clusters, like the Dipper or Great Bear and Cassiopeia, when night fell; to know how they change their position like the sun as night goes on, and to notice how one star, the Pole Star, is always seen above the same point on the horizon, in the same place at sunset and at sunrise.