The scene _may_ have really occurred before, or may be the result of a malady of perception, or one hemisphere of the brain not working in absolute simultaneousness with the other may produce a double impression, the first being followed by the second, so that we really have had two successive impressions, of which one seems much more remote in time than it really was.

Or we may have dreamed something like the scene and forgotten the dream, or we may actually, in some not understood manner, have had a "prevision" of what is now actual, as when Shelley almost fainted on coming to a place near Oxford which he had beheld in a dream.
Of course, if this "prevision" could be verified in detail, we should come very near to dreams of the future fulfilled.

Such a thing-- verification of a detail--led to the conversion of William Hone, the free-thinker and Radical of the early century, who consequently became a Christian and a pessimistic, clear-sighted Tory.

This tale of the deja vu, therefore, leads up to the marvellous narratives of dreams simultaneous with, or prophetic of, events not capable of being guessed or inferred, or of events lost in the historical past, but, later, recovered from documents.
Of Hone's affair there are two versions.

Both may be given, as they are short.