For often, when one is asleep, there is something in consciousness which declares that what then presents itself is but a dream.
AristotleThe soul consists of two parts, one irrational and the other capable of reason. (Whether these two parts are really distinct in the sense that the parts of the body or of any other divisible whole are distinct, or whether though distinguishable in thought as two they are inseparable in reality, like the convex and concave of a curve, is a question of no importance for the matter in hand.)
Aristotle