← Encyclopedia of Astrology · lesson 231/235
Decumbiture
First, plainly
A decumbiture belongs to the history of astrology and medicine. It is described here as heritage and symbolism — how earlier physicians thought — and it cannot diagnose, predict the course of an illness or replace medical care. For anything about your own health or anyone else's, see a doctor or another qualified professional.
What it is
A decumbiture is a chart cast for the moment a person took to their bed with an illness — the word comes from the Latin decumbere, "to lie down". It was one of the main tools of astrological medicine in Europe from the Middle Ages to the seventeenth century, when many physicians cast charts as a matter of routine.
The thinking was the same as for any beginning: the start of an illness was treated as a kind of birth, and its chart was read for the nature of the complaint and how it was expected to unfold. When the exact moment could not be known, physicians used another one instead — often the moment the patient's message, or a sample, reached them, which made the method close to horary astrology applied to sickness.
How it was read
Traditional practitioners looked at a few things above all.
- The Moon. Its sign and its condition at the decumbiture were read as the heart of the matter. Culpeper and Lilly give long lists: the Moon in a particular sign afflicted by Saturn or Mars, for instance, was associated with a particular kind of complaint in the vocabulary of the four humours — hot, cold, moist and dry.
- The houses. The First House and its ruler stood for the patient, the Sixth House for the illness, the Seventh House for the physician, the Tenth House for the treatment, and the Eighth House for the gravest outcome.
- The zodiac man. The sign of the Moon and of the afflicting planets pointed, through the old mapping of signs to the body, to the part of the body thought to be involved.
- The critical days. This is the part of the method most often remembered. Following Galen's teaching on crises, the Moon's motion from its place at the decumbiture marked the turning points: its first square, about seven days on, its opposition about a fortnight on, its second square about three weeks on. These were the critical days, when the illness was expected to turn one way or the other. Culpeper added lesser "judicial" days at the Moon's semi-squares and sesquiquadrates. How the Moon was aspected on those days was read as a sign of how the turn would go.
In the tradition
The best-known English texts are Nicholas Culpeper's Astrological Judgement of Diseases from the Decumbiture of the Sick (1655) and the sickness chapters of William Lilly's Christian Astrology (1647). The casebooks of the physician-astrologers Simon Forman and Richard Napier, who between them recorded tens of thousands of consultations around 1600, show how routine the practice was. It faded as medicine moved away from astrology in the eighteenth century, and survives now mainly among historians and traditional astrologers who study it as part of the craft's past.
Keeping it in perspective
A decumbiture is a window on a worldview in which the body and the sky were thought to move together. It is worth knowing because it explains a good deal of traditional astrology — why the sixth house is linked with illness, why the Moon's cycle was watched so closely — and because its language survives in everyday words like "crisis" and "critical". It is not a method to apply to a real illness: modern medicine, not a chart, is the right guide to anyone's health.