Geography

​And I do not know how Poseidonius, while showing the Phoenicians to be clever in other matters, has in this case accused them of stupidity rather than shrewdness. For day and night are measured by the revolution of the sun, which is at one time under the earth and at another time appearing above the earth. And he says that the movement of the ocean undergoes an astronomical period, rendering a daily, a monthly, and a yearly period, in sympathy with the moon. For whenever she rises above the horizon by the size of a zodiacal sign, the sea begins to swell and visibly encroach upon the land until she reaches the meridian. But when the star declines, the sea retreats again little by little until the moon is above the setting horizon by a zodiacal sign; then it remains in the same state for as long a time as the moon approaches the actual setting, and still further, for as long a time as, having moved under the earth, it is distant from the horizon by a zodiacal sign; then it encroaches again until its transit of the meridian under the earth; then it retreats until the moon, having moved around toward the east, is distant from the horizon by a zodiacal sign, and it remains so until she is elevated above the earth by a zodiacal sign, and then it encroaches again; this, he says, is the daily period. As for the monthly period, the greatest tides occur about the conjunctions, then they decrease until the first quarter; and again they increase until the full moon, and decrease again until the last quarter; then up to the conjunctions are the increases; and the increases exceed both in duration and in speed. And he says that he learned about the annual periods from the people in Gadeira, who say that at the summer solstice especially, both the retreats and the encroachments increase to the maximum. But he himself conjectures that from the solstice they decrease until the equinox, and increase until the winter solstice; then they decrease until the spring equinox, and then increase until the summer solstice. But since these periods occur during each day and night, the sea twice encroaching and twice retreating during the combined time, and both the daytime periods and the nighttime periods being regular, how is it possible that the filling of the well should often coincide with the ebb tides, but its lack of water should not often? Or often indeed, but not equally often? Or even equally often indeed, but that the Gadeiritans were not capable of observing these things which happen daily, yet observed the annual periods from things that happen once a year? And yet, that he indeed believes them is clear from the fact that he also conjectures the decreases and again the increases to happen from one solstice to the other, and the returns from there again. And besides, neither is that plausible, namely, that though they were observant, they did not see the things that do happen, but believed in things that do not happen.