Medical Astrology

Medical astrology was the branch of astrology that physicians and astrologers used alongside medicine from antiquity until the early modern period. It rested on three ideas that the texts stated plainly. The twelve signs each stood for a region of the frame, from the top down. The seven classical planets each stood for a set of parts and functions. And the hot, cold, moist and dry qualities that Greek medicine used to describe a patient were the same qualities the astrologers used to describe signs and planets, so one language served both crafts.

The earliest surviving version of the sign list is in the Astronomica of Manilius, a Latin poem of the first century. Ptolemy, writing in Greek in the second century, took a different route in the Tetrabiblos. He described the planets by their qualities in Book I, and in Book III he set out which parts each planet signified and how an astrologer judged a nativity for them. Galen, a physician of the same century, supplied the medical half of the pairing. His humoral medicine explained a patient by the balance of four fluids and their qualities, and that scheme became the common ground on which astrology and medicine met for the next fifteen hundred years.

In the Latin Middle Ages the pairing was taught in universities, and a figure of a man marked with the twelve signs circulated in manuscripts and then in print. The practice reached its fullest English statement in the seventeenth century. William Lilly’s Christian Astrology of 1647 gave the signs, planets and houses their medical meanings among everything else a horary astrologer judged. Nicholas Culpeper, a London apothecary and physician, wrote the English handbooks of the 1650s, including a treatise on judging a patient’s case from the chart cast at its onset.

The pairing came apart in the eighteenth century. Medicine moved toward observation at the bedside, toward chemistry and toward anatomy, and the faculties stopped teaching astrology as part of a physician’s training. Histories of medicine such as Roy Porter’s describe the shift as gradual rather than a single break, and the almanacs went on printing the figure long after physicians had stopped using it. What remains is a set of texts, a figure and a method. The texts can be read, the figure can be drawn, and the method can be run on any chart as a demonstration of how the old astrologers worked.

The Zodiac Man is a drawing of a standing figure with the twelve signs placed on it from Aries at the head to Pisces at the feet. The tradition called the list melothesia, from the Greek for the placing of limbs. The figure appeared in medieval manuscripts, in Books of Hours, the Très Riches Heures of the Duke of Berry being the best known, and in the cheap printed almanacs sold every year in England from the sixteenth century onward.

The figure served the almanac reader as a calendar key. The Moon passes through one sign roughly every two and a half days, and the almanacs listed which sign it occupied on each day. The texts held that a region ought not to be cut or bled while the Moon stood in the sign assigned to it, so the figure told a barber-surgeon which days the rule marked for each region. That use is history. The calendar page on this site shows the Moon’s sign and the region the texts assigned to it, and nothing more.

The table below gives the sign, the region and the planet the tradition assigned as ruler, with a column for each of the four sources this site follows. The sources agree in outline and differ in detail. Manilius gave Leo the flanks where Ptolemy and the English writers gave it the heart and back. Lilly and Culpeper split some regions more finely than the Latin and Greek texts, naming the throat under Taurus and the hands under Gemini where Manilius named the neck and the arms. The figure on this page links each region to its sign page, where the same assignment is set out in the sign’s own terms.

The seventeenth-century texts judged a nativity for vigor and constitution in a fixed order, and the order mattered more than any single placement. Lilly set out the method in the third book of Christian Astrology, and Culpeper followed the same sequence in his handbooks. First came the Ascendant and the planet that ruled its sign, which the texts held to signify the constitution as a whole. Then came the Sun and the Moon, the Sun by day and the Moon by night, as the lights of life. Then came the 6th house, its cusp sign and its ruler, which the texts assigned to sickness. Last came the temperament, a tally of hot, cold, moist and dry votes cast by the Ascendant, the Moon, the ruler and the season.

The walk below runs that method on the chart of Frida Kahlo, the painter, whose birth time is on record. The chart is a specimen of the method and nothing else. Nothing on this page or elsewhere on the site reads it for her health or her life, and no step below says what the chart meant for her.

Step one, the Ascendant. Kahlo’s Ascendant falls in Leo, which the texts assigned to heart and back. Its ruler, the Sun, is placed in Cancer in the eleventh house. An astrologer of Lilly’s time looked first at that ruler: its sign, its house, its aspects to the lights and to Saturn and Mars, and whether it stood near the Sun.

Step two, the lights. Kahlo was born by day, so the texts gave the first place among the lights to the Sun. The Sun stands in Cancer and the Moon in Taurus, in the balsamic phase of its cycle. Lilly read the Sun and the Moon as the two givers of life, the Sun by day and the Moon by night, and judged each by its sign, its house and the planets that aspected it.

Step three, the 6th house. The cusp of Kahlo’s 6th house falls in Capricorn, and its ruler, Saturn, is placed in Pisces. The texts read the 6th house for sickness and the 1st for the native, and looked at how the two rulers stood to each other. A planet inside the 6th house was listed as well, with its own sign and nature. The sign pages for the 6th house set out what the texts said for each cusp sign in turn, and the series of planet pages does the same for each ruler.

Step four, the temperament. Each factor in the method casts one vote for hot or cold and one for moist or dry: the Ascendant sign, the sign of its ruler, any planet in the 1st house, the Moon’s sign, the Moon’s phase, the planets in aspect to the Moon, and the season of the Sun. Kahlo’s chart tallies three hot votes to two cold, and four dry to one moist, which the method labels choleric. The temperament calculator shows every vote so a reader can disagree with any one of them, and the explainer on the four temperaments sets out where the weighting comes from. The methodology page lists the house system, the orbs and the ephemeris the site uses for every figure above.

Seven calculators run pieces of the method above on a chart or on a chosen moment: the temperament tally, the Zodiac Man figure from a chart, the decumbiture chart, the critical days, the Moon sign calendar, and the positions of the asteroids Hygiea and Aesculapia. Each result panel says what a historical method marks for the chart and nothing more, and each tool links to the explainer that sets out where its rule comes from.

The explainers take the history and the method one topic at a time: the Zodiac Man and its sources, the planets as the texts described them, the 6th house, the four temperaments, decumbiture and the critical days, and Culpeper’s sorting of plants under the planets. Two series follow, one page for each sign on the 6th house cusp and one for each planet in the tradition.

No placement in a chart describes a body. The signs and planets of the texts were assigned to regions and functions by writers who worked within the medicine of their day, and the assignments were never tested as medicine in the sense a modern reader gives that word. Galenic medicine itself was replaced, and the astrological half of the pairing went with it. The pages under this hub set the assignments out as history, with the texts named, and they stop there.

That means three things for a reader of this site. A calculator result here says what a seventeenth-century method marks for a chart, and it does not say what anyone’s body is doing or is going to do. A sign page says what Manilius and Ptolemy assigned to the sign, and not what a person born under it is like. A person page records a documented fact from the public record once, with its date and source, and states that the chart neither predicted nor explains it.

Astrology is not a healthcare discipline, and nothing on this site has been screened by a clinician. The notice under the title and the notice above the related tools say so in the site’s voice. This section says so in the author’s. A reader who came here with a question about medicine has reached a page about the history of astrology, and the right place for that question is a licensed professional.