It is equally difficult to explain satisfactorily how it was that Sarah, the wife of Abraham, was also his sister. Abraham says positively to Abimelech, king of Gerar, who had taken Sarah to himself on account of her great beauty, at the age of ninety, when she was pregnant of Isaac: "And yet indeed she is my sister; she is the daughter of my father, but not the daughter of my mother, and she became my wife." The Old Testament does not inform us how Sarah was her husband's sister. Calmet, whose judgment and sagacity are known to every one, says that she might be his niece. With the Chaldæans it was probably no more an incest than with their neighbors, the Persians. Manners change with times and with places. It may be supposed that Abraham, the son of Terah, an idolater, was still an idolater when he married Sarah, whether Sarah was his sister or his niece. There are several Fathers of the Church who do not think Abraham quite so excusable for having said to Sarah, in Egypt: "It shall come to pass, when the Egyptians shall see thee, that they shall say, This is his wife, and they will kill me, but they will save thee alive. Say, I pray thee, thou art my sister, that it may be well with me for thy sake." She was then only sixty-five. Since she had, twenty-five years afterwards the king of Gerar for a lover, it is not surprising that, when twenty-five years younger, she had kindled some passion in Pharaoh of Egypt. Indeed, she was taken away by him in the same manner as she was afterwards taken by Abimelech, the king of Gerar, in the desert. Abraham received presents, at the court of Pharaoh, of many "sheep, and oxen, and he-asses, and men-servants, and maid-servants, and she-asses, and camels." These presents, which were considerable, prove that the Pharaohs had already become great kings; the country of Egypt must therefore have been very populous. But to make the country inhabitable, and to build towns, it must have cost immense labor. It was necessary to construct canals for the purpose of draining the waters of the Nile, which overflowed Egypt during four or five months of each year, and stagnated on the soil. It was also necessary to raise the town at least twenty feet above these canals. Works so considerable seem to have required thousands of ages. There were only about four hundred years between the Deluge and the period at which we fix Abraham's journey into Egypt. The Egyptians must have been very ingenious and indefatigably laborious, since, in so short a time, they invented all the arts and sciences, set bounds to the Nile, and changed the whole face of the country. Probably they had already built some of the great Pyramids, for we see that the art of embalming the dead was in a short time afterwards brought to perfection, and the Pyramids were only the tombs in which the bodies of their princes were deposited with the most august ceremonies.