They say also that there are seven zones of the heaven Basil, Hom. 3, in Hexaëmeron., one higher than the other. And its nature, they say, is of extreme fineness, like that of smoke, and each zone contains one of the planets. For there are said to be seven planets: Sol, Luna, Jupiter, Mercury, Mars, Venus and Saturn. But sometimes Venus is called Lucifer and sometimes Vesper. These are called planets because their movements are the reverse of those of the heaven. For while the heaven and all other stars move from east to west, these alone move from west to east. And this can easily be seen in the case of the moon, which moves each evening a little backwards.