Nicene and Post-Nicene Fathers: Series II/Volume IX/John of Damascus/An Exact Exposition of the Orthodox Faith/Book II/Chapter 19

Concerning Thought.

The faculty of thought deals with judgments and assents, and impulse to action and disinclinations, and escapes from action: and more especially with thoughts connected with what is thinkable, and the virtues and the different branches of learning, and the theories of the arts and matters of counsel and choice. Further, it is this faculty which prophesies the future to us in dreams, and this is what the Pythagoreans, adopting the Hebrew view, hold to be the one true form of prophecy. The organ of thought then is the mid-ventricle of the brain, and the vital spirit it contains.