A long series of observations put the Chaldaeans in possession of a theological astronomy, resting on a more or less chimerical theory of the influence of the celestial bodies on the events of nations and private individuals. Diodorus Siculus, writing towards the commencement of our era, has put us in possession of the most circumstantial details that have reached us with regard to the Chaldaean priests. At the head of the gods, the Assyrians placed the sun and moon, whose courses and daily positions they had noted in the constellation of the zodiac, in which the sun remained, one month in each. The twelve signs were governed by as many gods, who had the corresponding months under their influence. Each of these months were divided into three parts, which made altogether thirty-six subdivisions, over which as many stars presided, called gods of consultation. Half of these gods had under their control the things which happen above the earth, and the other half those below. The sun and moon and the five planets occupied the most elevated rank in the divine hierarchy and bore the name of gods of interpretation. Among these planets Saturn or old Bel, which was regarded as the highest star and the most distant from us, was surrounded by the greatest veneration; he was the interpreter _par excellence_--the revealer. Each of the other planets had his own particular name. Some of them, such as _Bel_ (Jupiter), _Merodaez_ (Mars), _Nebo_ (Mercury), were regarded as male, and the others, as _Sin_ (the Moon), and _Mylitta_ or _Baulthis_ (Venus), as females; and from their position relative to the zodiacal constellations, which were also called _Lords_ or masters of the _Gods_, the Chaldaeans derived the knowledge of the destiny of the men who were born under such and such a conjunction--predictions which the Greeks afterwards called horoscopes. The Chaldaeans invented also relations between each of the planets and meteorological phenomena, an opinion partly founded on fortuitous coincidences which they had more or less frequently observed. In the time of Alexander their credit was considerable, and the king of Macedonia, either from superstition or policy, was in the habit of consulting them. It is probable that the Babylonian priests, who referred every natural property to sidereal influences, imagined there were some mysterious relations between the planets and the metals whose colours were respectively somewhat analogous to theirs. Gold corresponded to the sun, silver to the moon, lead to Saturn, iron to Mars, tin to Jupiter, and mercury still retains the name of the planet with which it was associated. It is less than two centuries ago, since the metals have ceased to be designated by the signs of their respective planets. Alchemy, the mother of chemistry, was an intimately connected sister of Astrology, the mother of Astronomy.