The Three Modalities

The second grid over the signs sorts them by mode rather than element. Every fourth sign shares a modality, giving three groups of four: the quadruplicities of the older literature:

• Cardinal: Aries, Cancer, Libra, Capricorn.
• Fixed: Taurus, Leo, Scorpio, Aquarius.
• Mutable: Gemini, Virgo, Sagittarius, Pisces.

The seasonal logic

In the tropical arrangement the grouping has a tidy seasonal rationale: the cardinal signs open the seasons (the Sun enters them at an equinox or solstice), the fixed signs occupy each season's settled middle, and the mutable signs close a season and hand over to the next. Hellenistic writers called the groups tropical (turning), solid, and bicorporeal or double-bodied; Lilly's English is 'moveable, fixed, and common signs'.^[1][2][3]

The interpretive layer, labelled

On top of that structure the traditions build an interpretive reading of style: cardinal signs are traditionally associated with initiating, fixed signs with sustaining and consolidating, mutable signs with adapting and transitioning. The seasonal metaphor does the symbolic work: beginnings, middles, and turnings of a cycle.^[1][2]

Elements and modalities together give each sign its coordinates in the tradition's own map: exactly one sign is cardinal fire, exactly one is fixed water, and so on. That grid (not any single sign description) is the structural idea a beginner actually needs.