Sign Humors

Sign humors describe the constitutional climate supplied by the zodiacal signs. In traditional medical astrology, the signs do not act alone, but they provide the background in which planets, houses, and symptoms are judged. The local source base supports this through the element-quality framework and through Morris's repeated use of cold, hot, moist, and dry sign emphasis when he discusses constitution. (Ptolemy, Tetrabiblos, Book I, chs. 4-8; Morris, Cycles in Medical Astrology)

The four elemental climates

The standard humoral mapping of the signs is:

fire signs as hot and dry
air signs as warm and moist
water signs as cold and moist
earth signs as cold and dry

This is the sign-level equivalent of the four humors. It explains why a chart with strong fire can be read as more choleric, while one dominated by earth can be read as more melancholic.

How the local medical source uses sign climate

Morris gives simple but helpful examples of sign-based confluence. He notes that a person who easily gets cold and shows a predominance of cold signs presents a stronger cold pattern than someone whose chart factors fight one another. That is a practical way to use sign humors: as background testimony that either supports or complicates what the planets are saying. (Morris, Cycles in Medical Astrology, Introduction)

He also repeatedly returns to the hot, cold, moist, and dry matrix in his constitution chapter, which confirms that sign climate is not decorative. It is part of the diagnostic framework.

Why sign humors are not enough by themselves

Sign humors should be read as the climate, not the whole weather report. A hot-dry sign can host a cold-dry planet, and a cold-moist sign can be strongly altered by a hot, angular Mars. That is why medical astrology combines sign humors with Planetary Humors, house emphasis, and symptoms.

Mercury is a good example of why the system needs more than signs alone. Since Mercury often takes on the nature of what it joins, a Mercurial placement in a sign does not automatically settle the temperament.

Practical use

Sign humors are most useful for:

seeing the basic climate of the chart
checking whether symptoms and planets agree with that climate
identifying mixed constitutions
locating where sign-based anatomy may carry heat, cold, moisture, or dryness

That makes this page a bridge between Four Humors and Body Parts by Sign.