What is hidden

Solitude, institutions, what works on you unseen.

The twelfth is cadent, and the last — the house immediately above the Ascendant, which is to say the part of the sky that rose most recently. Anything here was above the horizon at birth by less than two hours.

Classically Bad Daimon, and the house where Saturn rejoices. Solitude, confinement, institutions, self-undoing, and in modern readings anything that operates on a life without being watched.

It is also, with the first, the sixth and the seventh, the most variable house in the chart. At 50°N the twelfth can be as narrow as 16° or as wide as 58° depending only on what is rising; at 65°N it can collapse to five degrees. Whether a planet lands in the twelfth or the eleventh is, more often than for any other pair, a question about geometry.

Cadent, which is the houses' mutable

Houses 3, 6, 9 and 12 — each falling away from an angle toward the next. They are the transitional houses, and in quadrant systems they are usually the narrowest.

The parallel with the signs is exact rather than a metaphor. Cardinal signs sit three apart in the zodiac; angular houses sit three apart in the wheel. Both divisions are the circle cut into three, and both put the opening term at the point where something begins — an equinox or solstice for the signs, an angle of the chart for the houses. This house shares its class with the third, sixth and ninth.

How wide it really is

Placidus and the other quadrant systems divide time, not arc, so a house's width in the zodiac depends on which degree happens to be rising — and that changes through the day and with the latitude of the birthplace. Sampled every ten minutes across a full rotation, here is how far the twelfth house stretches:

The mean is 30° at every latitude, and that is not a coincidence or an artefact of the sampling: over a full rotation each house passes across the entire zodiac, so twelve houses sharing 360° must average exactly thirty. All of the inequality is in the spread, which is why an averaged figure tells you nothing and the range tells you everything. The sixth house has an identical span in every chart, since its cusps are exactly 180° from this one.

Traditionally attributed

Retreat, confinement, self-undoing, and what works unseen.

Listed because it is what the tradition says, not because this site can check it. Everything above this line is geometry; everything in it is convention.