Astrology and medicine: a historical connection

Until the seventeenth century, astrology was part of medical training. At several European universities it was on the curriculum of the medical faculty. This is well documented and worth a closer look — precisely because nothing follows from it for present-day practice.

What happened then

The connection was not loose but systematic, and it rested on a shared framework: the doctrine of the four qualities.

Medicine and astrology shared the same system of hot, cold, dry and moist. An illness was an excess of one quality; a remedy worked through the opposite one. And because the planets and signs were defined by those same qualities, the two could be joined.

Specifically, astrology was used for three things:

• The constitution — the temperament taken from the birth chart, as a basis for what a person tends towards and what agrees with them.
• The course of the illness — the decumbiture, the chart for the moment the sick person took to their bed, read through the course of the Moon and the critical days.
• The timing — the choice of moment for bloodletting or surgery, usually with an eye to the Moon's position in the sign that rules the affected part of the body.

Why it ended

Not through a ban, but because the foundation fell away. In the eighteenth and nineteenth centuries, humoral pathology was displaced by anatomy, physiology and finally germ theory. With it went the shared framework through which the connection ran.

Astrology, then, did not lose a dispute about its effectiveness. It was deprived of the conceptual apparatus on which it depended within medicine.

What holds today

This has to be unmistakable: A chart does not make a diagnosis.

There is no evidence that an illness can be read off a planetary position. Anyone who tries does harm in two ways: a false alarm creates fear of something that is not there. A false all-clear keeps someone from seeing a doctor — and that can end in death.

That is why serious practitioners refuse to make medical statements, even when they are expressly asked for them. This is not caution on legal grounds but the consequence of what the technique can deliver.

What remains interesting

The history itself. Medical astrology is one of the best documented areas of application in the tradition — with surviving collections of cases in which physicians recorded their charts, their judgements and the course each illness took.

These collections are one of the few sources in which astrological judgements have come down together with their outcome. For the question of what the technique can do, they are worth more than any modern account.

See also: the four elements and the doctrine of temperaments.