Advanced Concepts
Decan
Each sign divided into three 10° sections with sub-rulerships.
Each zodiac sign spans 30° and is divided into three decans (or decanates) of 10° each. Each decan has a sub-ruler that adds nuance to the sign's expression. For example, Aries is sub-ruled by Mars (1st decan), Sun (2nd), and Jupiter (3rd). Understanding your planets' decans adds depth to interpretation - two people with Sun in Aries but in different decans will express it differently.
Example
First decan Aries (0-10°) is the purest Aries energy. Third decan Aries (20-30°) has Sagittarian/Jupiter influence, adding philosophy to the warrior.