Science 161 discoveries may necessitate considerable modification of the con- clusions expressed in this chapter. Calendar The outstanding achievement of the Ancient Egyptians in science was the introduction of the first practical calendar. It is dealt with in Chapter I. Astronomy Star diagrams were made at a very early date, the stars being grouped in constellations according to a fancied resemblance to some animate or inanimate form. The grouping, however, was not the same as our own, which derives from the Babylonians. Several examples of star diagrams survive on the ceilings of temples and tombs and on the interior surfaces of coffin lids. They were supposed to be of some use to the deceased in his journeyings in the netherworld. They do not exhibit the differ- ences one would expect, had they been intended for horoscopes as some writers have suggested. Generally speaking, they con- form to a standard pattern with comparatively minor variations. The keeping of the calendar being in the hands of the priests, special value was attached to the selection of the proper days for religious observances. The sun and moon played a large part in priestly cosmology and mythology. In the literature available are references to the planets ('the stars who never rest5), and in particular to Venus ('the morning star5 or 'the evening star5 — in early times probably differentiated); Jupiter ('the resplendent star'); Saturn ('Horus, the Bull5); Mars (cthe red Horus'), and possibly Mercury. A map of the heavens, specially prepared to show the positions of the principal stars as seen from Memphis about 3500 B.C., enables us to identify some of the star groups figured in the ancient star maps. At that date the 'Great Bear' was con- spicuous in rotating round the pole and was named the 'ox-leg*.