The so-called exaltations of the planets have the following explanation. Since the sun, when he is in Aries, is making his transition to the northern and higher semicircle, and in Libra is passing into the southern and lower One, they have fittingly assigned Aries to him as his exaltation, since there the length of the day and the heating power of his nature begin to increase, and Libra as his depression for the opposite reasons.
Saturn again, in order to have a position opposite to the sun, as also in the matter of their houses, look, contrariwise, Libra as his exaltation and Aries as his depression. For where heat increases there cold diminishes, and where the former diminishes cold on the contrary increases. And since the moon, coming to conjunction in the exaltation of the sun, in Aries, shows her first phase and begins to increase her light and, as it were, her height, in the first sign of her own triangle, Taurus, this was called her exaltation, and the diametrically opposite sign, Scorpio, her depression.
Then Jupiter, which produces the fecund north winds, reaches farthest north in Cancer and brings his own power to fullness; they therefore made this sign his exaltation and Capricorn his depression.
Mars, which by nature is fiery and becomes all the more so in Capricorn because in it he is farthest south, naturally received Capricorn as his exaltation, in contrast to Jupiter, and Cancer as his depression.
Venus, however, as she is moist by nature and increases her own proper power all the more in Pisces, where the beginning of the moist spring is indicated. has her exaltation in Pisces and her depression in Virgo.
Mercury, on the contrary, since he is arier, by contrast naturally is exalted, as it were, in Virgo, in which the dry autumn is signified, and is depressed in Pisces.