Al-Ghazālī (c. 1058-1111)
“With your question you have climbed a difficult slope, one before whose upper regions the eyes of the observers fall back. You have knocked at a locked door that is not to be opened except for the firmly rooted possessors of knowledge.”
- From The Niche of Lights by Al Ghazālī, translated by David Buchman. Utah: Brigham Young University Press, 1998.