OR THE QUADRIPARTITE MATHEMATICAL TREATISE
10. Of the Effect of the Seasons and of the Four Angles.
Of the four seasons of the year, spring, summer, autumn, and winter, spring exceeds in moisture on account of its diffusion after the cold has passed and warmth is setting in; the summer, in heat, because of the nearness of the sun to the zenith; autumn more in dryness, because of the sucking up of the moisture during the hot season just past; and winter exceeds in cold, because the sun is farthest away from the zenith. For this reason, although there is no natural beginning of the zodiac, since it is a circle, they assume that the sign which begins with the vernal equinox, that of Aries, is the startingpoint of them all, making the excessive moisture of the spring the first part of the zodiac as though it were a living creature, and taking next in order the remaining seasons, because in all creatures the earliest ages, like the spring, have a larger share of moisture and are tender and still delicate. The second age, up to the prime of life, exceeds in heat, like summer; the third, which is now past the prime and on the verge of decline, has an excess of dryness, like autumn; and the last, which approaches dissolution, exceeds in its coldness, like winter.
Similarly, too, of the four regions and angles of the horizon, from which originate the winds from the cardinal points, the eastern one likewise excels in dryness because, when the sun is in that region, whatever has been moistened by the night then first begins to be dried; and the winds which blow from it, which we call in general Apeliotes, are without moisture and drying in effect. The region to the south is hottest because of the fiery heat of the sun's passages through mid-heaven and because these passages, on account of the inclination of our inhabited world, diverge more to the south; and the winds which blow thence and are called by the general name Notus are hot and rarefying. The region to the west is itself moist, because when the sun is therein the things dried out during the day then first begin to become moistened; likewise the winds which blow from this part, which we call by the general name Zephyrus, are fresh and moist. The region to the north is the coldest, because through our inhabited world's inclination it is too far removed from the causes of heat arising from the sun's culmination, as it is also when the sun is at its lower culmination; and the winds which blow thence, which are called by the general name Boreas, are cold and condensing in effect.
The knowledge of these facts is useful to enable One to form a complete judgement of temperatures in individual instances. For it is easily recognizable that, together with such conditions as these, of seasons, ages, or angles, there is a corresponding variation in the potency of the stars' faculties, and that in the conditions akin to them their quality is purer and their effectiveness stronger, those that are heating by nature, for instance, in heat, and those that are moistening in the moist, while under opposite conditions their power is adulterated and weaker. Thus the heating stars in the cold periods and the moistening stars in the dry periods are weaker, and similarly in the other cases, according to the quality produced by the mixture.