The most widely know astrological concept
Signs indicate where in the zodiac a planet is. The signs are derived by division of the zodiac into 30 sections from 0° Aries, an astronomically derived point.
They describe how the planet will manifest; the manner of the planet’s energy. If you imagine a church with a stained glass window, as the light goes through the window it picks up some of the qualities of the glass. So the planet will always have its core qualities but it will be expressed in a different way depending on the sign.
Many astrology books talk about Sun in Aries rather than the principle of Aries. It is important to realise you can have the sign in a pure form, and that you could have strong Virgo energy, for instance, without actually having the Sun in Virgo.
The essential dignity of a planet and the receptions with other planets is derived from their zodiacal position. See the section on Essential Dignity in the Concepts section.