[to my mind] when you're hallucinating, you have an absolutely clear proof that you are not generating this material. Its not funny ideas, its not racing thoughts, its not insight into what your boyfriend really meant yesterday. That kind of thing we can all generate by just inspecting our own minds. But a hallucination is to be in the presence of that which could previously not be imagined. And if it could previously not be imagined, then there is no grounds for believing that you generated it out of yourself.
I mean, we should each know our own inventory. You know what's in your cupboard, you know what's in your chest of drawers, for God's sake, you ought to know what's in your mind. Then if something comes forward, and you say, "That's not mine, That's not in my inventory," then you have a kind of perfect proof that this is coming from somewhere else. Then the question becomes, where? And we can set off into that, opinions differ and nobody has God's truth on it.
Eros and the Eschaton