Medieval Map of the Hemispheres

This Medieval map shows the northern and southern hemispheres, with the constellations drawn to represent the stars’ positions. Although it is likely ordinary Europeans could point out different patterns in the sky, you had to have elite training to be able to pass yourself off as a real star-gazer: it was totally normal for people to assume that an elaborate understanding of the planets would entail an ability to draw conclusions about how the celestial bodies were shaping events on earth. And thus, when the Great Death came through in the mid- 14th century, public officials turned to astrologers/astronomers (same difference at the time) to explain why the pestilence was so horrific.

King Philip IV of France asked the Medical University faculty at Paris for an explanation, and they put together a plague response in 1348 that assured that a conjunction of Saturn, Mars, and Jupiter in the constellation of Aquarius in March of 1345 had caused the air close to the surface of earth to be corrupted.
In fact, the man who developed the term “Black Death,” named Simon de Covino wrote a lengthy Latin poem on the subject called “On the Judgement of Sol at the feasts of Saturn” in which he elaborates with exquisite detail how all the forces of the celestial bodies interconnected to create the pandemic. He anthropomorphasized the planets, stating that Sol, the sun, was a judge over the destructive Saturn and peaceful Jupiter. It turns out that warlike Mars and a lunar eclipse also played a role in his equation.

The sorts of naturalist explanations were of course totally wrong, but as historian Rebecca Johnson points out, it was a sort of step forward for science to allow for an understanding of how the world operates outside of the moralistic explanations that were usually offered. After all, if you think the planets caused your bad day, you won’t be tempted to persecute people whose religion differs from your own as a way to fix the situation.