In the summer of 1467, the Hungarian King Mathias 1 Corvinus hosted a public contest to find the time of conception of the newborn son of Countjohann von Rosgou by astrological means.1 Around the same time, the King sponsored the completion of Regiomontanus’s astrological tables, by which “the times of all future events are chiefly investigated.”2
Regiomontanus’s successors increasingly preferred to distance themselves from astrological practice. In 1600, Tycho Brahe sent the following reply to a request for astrological counseling:
I do not freely devote much time to such issues, being more addicted
to serious and momentous studies.3
Twenty years later, his former assistant Joannes Kepler introduced a prognostication for 1620 as follows:
If I only put forward what the heavens provide, men the calculation of
an annual ephemeris would absolve the matter, and I would retain my
fame in this annual exercise without being contradicted by anyone.4
What caused this apparent defection among elite astrological practitioners? The question has been addressed in this book through a detailed study of the Louvain astrological community, which was located at the border of the Holy Roman Empire.
The University of Louvain was erected in 1425, at the end of the first wave of German university foundations. Its medical faculty soon became home to a flourishing community of astrological practitioners.
1 Zinner, Regiomontanus, trans. Brown, p. 94.
2 Regiomontanus, Tabulae directionum (1552), vol. 1, fols. b1v-b2r: “(…) ubi tem-
pora futurorum accidentium omnium per directiones potissimum investigari soient.”
3 Brahe, Opera, vol. 8, p. 305:1–3.
4 Kepler, Gesammelte Werke, vol. xi.2, p. 196: “(…) wann ich allein das jenige
einbringen soke, was der Himmel gibt, so ware mit calculierung einer Ephemeridis