Astrology & myths · Hellenistic astrology · Ptolemy, Tetrabiblos I.4
Ptolemy's Sun: heating, and somewhat drying
In the second century, Ptolemy described each planet's power in terms of four qualities. The Sun's was the simplest.
The passage
In Robbins's translation, the Sun's active power is heating and, to a certain degree, drying. The same chapter goes on to give each of the other planets its own mixture of the four qualities.
How the system works
That is a system for reading symbols, built from the physics of its own time. Modern science explains the Sun's heat with fusion in its core; the two are not competing answers to the same question, and this site does not treat the first as a prediction.
Astrology and myth are presented here as symbolic and historical traditions, not as predictions. The sky's positions and times on this site are calculated the same way in every lens.
Sources
- LacusCurtius (Bill Thayer) Ptolemy, Tetrabiblos, Book I, ch. 4–24 (trans. F. E. Robbins, Loeb 1940) (opens in a new tab) for the Sun heats and somewhat dries (I.4); diurnal (I.7); house Leo (I.17); exalted in Aries, depressed in Libra (I.19) · checked 2 October 2026
- NASA Science How does the Sun make energy? (opens in a new tab) for fusion of hydrogen into helium in the core; balance of pressure and gravity · checked 2 October 2026