Cardan Synes Somn.
But I was intrigued and went looking and found an article that had no reference to Goethe, but was suggestive of what might have interested Goethe in Cardano's dream book. The article is by Jacomien Prins, and it concerns a seminar held between 1936 and 1941 conducted by the psychologist Carl Gustav Jung, during which he discussed twelve of Cardano's dreams, which apparently appeared in the Latin-titled work that Goethe read. I will be paraphrasing from this article, which appeared in I Tatti Studies in the Italian Renaissance (vol. 20, no. 2, 2017).
Cardano is most well known for his work in mathematics, but we can assume that his math was not Goethe's interest, but, instead, the more arcane aspects of the Renaissance thinker. Cardano was, for instance, an astrologer. According to Prins, Cardano was also “one of the most important Renaissance pioneers to revive the ancient dream interpretation.” Here is a sentence from the first paragraph of the article that one can imagine might have had some resonance for Goethe: “Central to Cardano’s dream theory is the idea that the cosmos is a dynamic network of occult harmonic correspondences, knowledge of which can be revealed in dreams.”
Cardano kept a night diary in which he recorded his dreams. He believed that dreams, being about the dreamer's present situation, should be consulted for inferences they contain for the future. According to Prins, the great trauma of Cardano's life was the death of one of his sons, who was executed for murdering his wife. Cardano kept asking himself whether, had he paid more attention to warning signals in his dreams, he could prevented this tragic course of events. Cardano wrote, for instance: “I had a warning, also, in 1547, in the summer at Pavia while my younger son was sick, lying, as it were, at the point of death, that I should be bereft of the object of my affection.”
In this connection, I can't help considering that Goethe might have been seeking some solace after the family tragedy of the month before, the death of his sister Cornelia. The few comments that Goethe made about his sister suggest a certain guilt concerning her unhappy situation after her marriage.