[jhanschoo]

> > A large part of our civilisation rests on the shoulders of one medieval monk: Thomas Aquinas.

For such a grandiose claim, I was honestly thinking of another churchman, though not a medieval monk: Augustine of Hippo

Free will as a mental phenomenon (rather than political freedom), Christian original sin, Western prudence and chastity are some notions that I think were extremely heavily influenced by him, or originated from him.