Nor, if the things themselves are not worth remembering, or worthy of influencing us, is there any good in enquiring concerning them?
Shall I mind a thing that is not worth minding, because it came to me in a dream, or was told me by a ghost?
It is the quality of a thing, not how it arrived, that is the point.

But true things are often mingled with things grotesque.
For aught I know, at one and the same time, a spirit may be taking advantage of the door set ajar by sleep, to whisper a message of love or repentance, and the troubled brain or heart or stomach may be sending forth fumes that cloud the vision, and cause evil echoes to mingle with the hearing.

When you look at any bright thing for a time, and then close your eyes, you still see the shape of it, but in different colours.

This figure has come to you from the outside world, but the brain has altered it.

Even the shape itself is reproduced with but partial accuracy: some imperfection in the recipient sense, or in the receptacle, sends imperfection into the presentation.