The twelve signs

A planet is one thing. A planet in a sign is that same thing, seen through a filter.

This is the distinction to hold onto, because the whole lesson rests on it: the sign does not change what a planet is. It changes how it goes about it. Mars in Aries and Mars in Scorpio are the same planet with the same nature — hot, dry, sharp. In Aries, a cardinal fire sign, that nature points outward and moves first. In Scorpio, a fixed water sign, it turns defensive, holds position, and answers rather than opens. One planet, two manners.

The zodiac we use is tropical: twelve equal arcs of thirty degrees, measured from the spring equinox at zero Aries, as Lesson 1 set out.