The Conjunction Blamed for the Black Death

When plague reached Paris, the king demanded an explanation from the highest medical authority in Europe. The faculty of the University of Paris delivered their report to Philip VI in October of 1348, and their first cause was not rats, nor ships, nor sin. It was a date: the twentieth of March, 1345, when Jupiter, Saturn, and Mars stood together in Aquarius.

The instruments below hold that evening as the engine computes it. Jupiter and Saturn within a third of a degree. Mars in the same sign, closing. The faculty's date was not rhetoric — it was an observation, and it checks out to the degree across nearly seven centuries.

What the doctors were taught to see

Royal Library of Belgium, MS 13076-77 · via Wikimedia Commons · Public domain

The doctrine they applied was older than their university. Jupiter meeting Saturn marks the turning of eras — the watchers of Babylon counted these meetings, and Abu Ma'shar built the clock of history upon them, as the wise men once followed a meeting of the same two planets west. Add Mars, the lesser malefic, hot and dry, and the reading darkens: Jupiter draws up rot from earth and water, Mars ignites it, Saturn seals it over a whole age. Corrupted air — miasma — carried on the winds to whole peoples.

The report's architecture is worth seeing, because it is rigorous by its own lights. The masters argued three orders of cause. The universal and remote cause: the configuration of 1345, corrupting the air from above. The particular and near cause: the vapors of earth and water — rot, marsh, and exhalation — which the corrupted air drew up and spread on the winds. And the disposition of each body: why one man sickened while his neighbor was spared, answered through complexion and temperament. Remote cause, near mechanism, individual susceptibility — the skeleton of the explanation is recognizably the shape of medicine still, with only the contents exchanged.

Nor was the astrology ornamental to their training. The medical faculties of Bologna and Padua maintained chairs of astrology beside anatomy; a physician was expected to time bleeding and purging by the Moon's sign and phase, and the medicus who could not find the Moon was, in the era's own judgment, no physician. When Paris answered the king with a conjunction, it was practicing its discipline exactly as taught.

Their medicine failed. Their timekeeping did not. Within three years of the meeting, a quarter of Europe was in the ground, and the learned world did not ask whether the sky had caused it or merely announced it. That distinction is modern. To them, the warning stood written above before it arrived below — cause and omen were one sentence in one grammar.

What the record actually says

Read soberly, the report is the most consequential astrological document of the medieval world: the moment the art stood before a king, in an emergency, and answered with a computation. The computation was correct — the planets stood exactly where they said. The interpretation belonged to its age. Both facts deserve to be remembered together, which is how this record remembers them.

There is one more thing the document preserves: the pedigree of the method. The masters did not invent the dread of Jupiter–Saturn meetings in 1348 — they inherited it through Abu Ma'shar's doctrine of the great conjunctions, which had come into Latin a century earlier through the translators of Toledo, and which the watchers of Babylon had practiced in its oldest form two thousand years before that. A Parisian committee, a Baghdad astrologer, and a Chaldean priest stand in one unbroken line of men asked by power to read the sky in a crisis. The great mutation of 1603 belongs to the same line, and so does every reader who turns this record's own instruments to the same two planets.

Great meetings in the sky precede great turnings on earth — so the doctrine held, and 1345 became its most terrible witness. Turn the map to that evening yourself; the three are still standing there, in the cold sign of the Water-Bearer, a third of a degree apart.