"The middle cell of the head," according to Averroes in Chap. LX. If any one will have it that the grey matter of the brain is the organ even of intelligence itself, the scholastic reply is: 'Of intelligence as needing the concurrence of phantasms, yes: of intelligence pure and simple, exactly the nous chôristos, no.' The difficulty remains, that precisely over the most abstract thinking, where the thinker does his utmost to dispense with phantasms, does the grey matter of the brain get most exhausted. Perhaps the effort to dispense with phantasms does violence to the phantasy, and thereby consumes the tissue which ministers to that sentient faculty.
Of God and His Creatures: 2.73