[Illustration: PLAN OF MEMPHIS. (_From Lepsius._)] We have seen that it did not require any great amount of astronomical knowledge to determine either the moment of the solstice or the moment of the equinox. The most natural thing to begin with was the observation of the solstice, for the reason that at the solstice the sun can be watched day after day getting more and more north or more and more south until it comes to a standstill. But for the observation of the equinox, of course, the sun is moving-most rapidly either north or south, and therefore it would be more difficult to determine in those days the exact moment. [Illustration: EAST AND WEST PYRAMIDS AND TEMPLES AT GÎZEH. (_From Lepsius._)] We next come to the question as to whether any buildings were erected from an equinoctial point of view--that is, buildings oriented east and west. Nothing is more remarkable than to go from the description and the plans of such temples as we have seen at Abydos, Annu, and Karnak, to regions where, apparently, the thought is totally and completely different, such as we find on the Pyramid Plains at Gîzeh, at Memphis, Tunis, Saïs, and Bubastis. The orientation lines of the German surveyors show beyond all question that the pyramids and some of the temenos walls at the places named are just as true to the sun-rising at the equinoxes as the temples referred to at Karnak were to the sun-rising and setting at the solstices, and the Sphinx was merely a mysterious nondescript sort of thing which was there watching for the rising of the sun at an equinox, as the Colossi of the plain at Thebes were watching for the rising of the sun at the winter solstice. [Illustration: TEMPLE AND TEMENOS WALLS OF TANIS. (_From Lepsius._)] [Illustration: TEMPLE AND TEMENOS WALLS OF SAÏS (SĀ-EL-LAGER). (_From Lepsius._)]