Detriment
A planet is in detriment when it occupies the sign opposite the one it rules — its own house seen from the far side of the zodiac. It is read as active destruction: the planet is in circumstances working against it and has no means of changing them.
The fuller picture
The lookup is mechanical: take the sign a planet rules and cross to the sign opposite. Mars rules Aries, so Venus is in detriment there; Venus rules Libra, so Mars is in detriment there; and so on round the twelve. Two of the seven planets rule one sign each, so the Sun is in detriment only in Aquarius and the Moon only in Capricorn. On our table detriment scores minus five, which makes it the heaviest single essential penalty available and the exact mirror of domicile's plus five.
The reading that comes with it is specific, and it is worth having rather than a general sense of weakness. Detriment describes an active state of destruction — the person knows they lack the means or the ability to change their circumstances. In one chart the same debility is glossed as a deep loneliness, someone carrying burdens silently and without support. That is not the same as a planet being merely feeble. And it does not make a malefic harmless: a malefic in detriment is read as acting in a more warlike way, doing what it does as a means of ensuring its own survival, which is a good deal more dangerous than a malefic comfortably placed.
Detriment and fall are both debilities, and running them together loses a real distinction. Detriment is destruction. Fall is exaggeration — a situation genuinely bad, with the suffering out of proportion to it. Detriment is also not the same thing as peregrine, and this is where most of the confusion in this corner of the tradition sits. A peregrine planet holds no relationship at all to the sign it stands in; a planet in detriment holds a specific, hostile one. Our engine keeps the two apart by construction, excluding a planet in detriment or fall from the peregrine test on the ground that it has a bad relationship to the sign rather than no relationship — which also stops it being penalised twice for the same placement.
Two further things a definition drops. Detriment can sit alongside a dignity, because the five dignities and the two debilities are separate lookups: a planet can be in the sign opposite its own and in its own term at the same degree, and the engine sums the two into a single number. The practitioner's own instruction on that combination is blunt — a minor good cannot alter a major evil — so a small dignity should not be read as rescuing the placement. And reception can genuinely soften it: a significator in detriment that its dispositor receives is in a better state than one nobody has a claim on. The opposite arrangement carries its own weight: where one significator sits in the sign of the other's detriment, iHorary records it as a negative reception and reads the host as ill-disposed towards the guest — one testimony about the placement, not a settled verdict on anybody's attitude.
In your chart
Detriment has its own column in the dignities table, scored minus five and toned as an affliction rather than sitting in the same colour as the fortitudes, and it sums with any dignity the same planet holds. The planet dossier names it among that planet's dignities in the strongest-first list. In the judgment layer a significator carrying an essential score of minus four or worse is emitted as a major negative testimony, and one significator sitting in the other's detriment is recorded separately as a negative reception.
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