Mutable

Gemini, Virgo, Sagittarius and Pisces are the signs the Sun occupies in the last month of each season, when one season is giving way to the next. Ptolemy calls them bicorporeal, disoma, meaning two bodied, and the reason he gives is that each shares the nature of the season it ends and the season it begins.

That is a stronger claim than the modern word mutable conveys. Bicorporeal says these signs have two natures at once, not that they change easily, and the tradition applies the term literally: three of the four are represented by double figures, the twins of Gemini, the two fish of Pisces, and the horse and man of Sagittarius. Virgo is the exception, and the reason usually given for including it is its position in the season rather than its image.

The reading that follows is adaptation, distribution and preparation. A mutable sign does not begin a thing and does not hold it; it carries it across, dividing and passing on what the fixed sign accumulated. The tradition also gives the group flexibility and inconstancy as two readings of one property, and does not treat either as the correct one.

Mercury and Jupiter rule the four between them in the traditional scheme, Mercury taking Gemini and Virgo and Jupiter taking Sagittarius and Pisces. It is a neat symmetry and the sources notice it.

Mutable is the modern name. The older English one is common, translating the Latin term for what is shared, and it means a sign belonging to two seasons rather than to one. Double bodied is the direct rendering of the Greek. All three are in print and all three name the same group.

The four stand at the ends of a cross, each in square or opposition to the other three, in the same way the cardinal and fixed groups do. Gemini and Sagittarius form the axis of learning near and far, and Virgo and Pisces the axis of service and dissolution, which is a modern formulation of something the older house lists imply without stating it.

There is a further technical use worth recording. In horary practice, a mutable sign on the relevant cusp is read as a sign of repetition or return: a matter that will recur, a person who will come back, a thing not finally settled. A cardinal sign on the same cusp is read for a quick outcome and a fixed sign for a lasting or immovable one. That triad of judgements is one of the places where the qualities do concrete work rather than describing temperament, and it belongs to the horary literature rather than the natal.

Unlike the cardinal ingresses, the Sun's entry into a mutable sign has no astronomical event attached to it. The group is defined by its position within the season, and that definition is the tradition's own rather than the sky's.

Sources Christian AstrologyWilliam Lilly with TetrabiblosClaudius Ptolemy