Authentic medieval/Renaissance European magic, more or less

[Apollonian]

I am trying to figure out how to implement "authentic" magic for Europe of the late middle ages and early Renaissance in GURPS. This is a bit ofa place holder post, because it's quite late, but I don't want to lose the thought.

I don't think classic spell magic is a thing, and the classic rational magic models GURPS is used to probably won't work tricky well either. Forms of magical arts I'm considering: astrology, alchemy, goetia, calling on divine power, "folk magic"... What am I missing?