They who talk thus may, with as much reason, if it be necessary to their hypothesis, say that a man is always hungry, but that he does not always feel it; whereas hunger consists in that very sensation, as thinking consists in being conscious that one thinks.

If they say that a man is always conscious to himself of thinking, I ask, How they know it?
Consciousness is the perception of what passes in a man's own mind.

Can another man perceive that I am conscious of anything, when I perceive it not myself?
No man's knowledge here can go beyond his experience.

Wake a man out of a sound sleep, and ask him what he was that moment thinking of.

If he himself be conscious of nothing he then thought on, he must be a notable diviner of thoughts that can assure him that he was thinking.
May he not, with more reason, assure him he was not asleep?
This is something beyond philosophy; and it cannot be less than revelation, that discovers to another thoughts in my mind, when I can find none there myself.