First, the diurnal motion of the whole heavens from east to west must have been noticed during the night, and the fact that certain stars never set, but turn in a circle round a fixed point. What becomes then, the next question would be, of those stars that do descend beneath the horizon, since they rise in the same relative positions as those in which they set. They could not be thought to be destroyed, but must complete the part of the circle that is invisible _beneath the earth_. The possibility of any stars finding a path beneath the earth must have led inevitably to the conception of the earth as a body suspended in the centre with nothing to support it. But leaving this alone, it would also be concluded that the sun went with the stars, and was in a certain position among them, even when both they and it were invisible. The next observations necessary would be that the zodiacal constellations visible during the nights of winter were not the same as those seen in summer, that such and such a group of stars passed the meridian at midnight at a certain time, and that six months afterwards the group exactly opposite in the heavens passed at the same hour. Now since at midnight the sun will be exactly opposite the meridian, if it continues uniformly on its course, it will be among that group of stars that is opposite the group that culminates at midnight, and so the sign of the zodiac the sun occupies would be determined. This method would be checked by comparisons made in the morning and evening with the constellations visible nearest to the sun at its rising and setting. The difficulty and indirectness of these observations would make it probable that originally the zodiac would be determined rather by the path of the moon, which follows nearly the same path as the sun, and which could be observed at the same time as, and actually associated with, the constellations. Now the moon is found each night so far to the east of its position on the previous night that it accomplishes the whole circumference in twenty-seven days eight hours. The two nearest whole number of days have generally been reckoned, some taking twenty-eight, and others twenty-seven. The zodiac, or, as the Chinese called it, the Yellow Way, was thus divided into twenty-eight parts, which were called _Nakshatras_ (mansions, or hotels), because the moon remains in each of them for a period of twenty-four hours. These mansions were named after the brightest stars in each, though sometimes they went a long way off to fix upon a characteristic star, as in the sixteenth Indian constellation, _Vichaca_, which was named after the Northern Crown, in latitude 40 deg.. This arose from the brightness of the moon extinguishing the light of those that lie nearest to it.