"You see you've got to realize what hypnotism is before you can know what it's like.

It's really the art of imposing one's will upon someone else's, of making that other person see things as you want them to see them--not as they really are.
It's the power of deception carried to a superlative degree.

And when that power is exhausted, the ticket may be said to have expired--and the prisoner returns to the dungeon.

Sometimes he takes the other person with him.

Sometimes he goes alone." He stopped abruptly as a hand rapped smartly on the door.
Avery looked up again from her work.