This is a question that cannot be avoided. It was put to Herodotus, more than two thousand years ago, by the peculiarities of the scene. He answered it after his fashion, which was that of his time. It was, he said, originally an arm of the sea, corresponding to the Arabian Gulf, the Red Sea; and had been filled up with the mud of the Nile. Those were days when, as was done for many a day afterwards, the answers to physical questions were sought in metaphysical ideas. The one to which the simple-minded, incomparable, old Chronicler had recourse on this occasion was that of a supposed symmetrical fitness in nature. There is the Red Sea, a long narrow gulf, a very marked figure in the geography of the world, trending in from the south, on the east side of the Arabian Hills. There ought therefore to be on the west side of this range a corresponding gulf trending in from the north: otherwise the Arabian Gulf would be unbalanced. That compensatory gulf had been where Egypt now is. The demonstration was complete. Egypt must have been an arm of the sea, which had been gradually expelled by the deposit from the river. This argument, however, is not unassailable, even from the fitness-of-things point of view. Had the fitness-of-things been in this matter, and in this fashion, a real agent in nature, it should have made the valley of Egypt somewhat more like the Red Sea in width; and it should also have interdicted its being filled up with mud. It should have had the same reasons and power for maintaining it, which it had originally for making it. In this way, however, did men when they first began to look upon the marvels of Nature with inquiring interest, suppose that metaphysical conceptions, creatures of the brain, were entities in Nature, and would supply the keys that were to unlock her secrets.