Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy (a branch of mathematics within the liberal arts) and physics (a branch of natural philosophy).
Kepler levede i en tid uden klar adskillelse mellem astronomi og astrologi, men der var en klar adskillelse mellem astronomi (en gren af matematik inden for de frie kunster) og fysik (en gren af naturfilosofi).