There is nothing more mysterious than the self-deluding power of the mind, and there never were scenes in which it was more clearly displayed than the witchcraft prosecutions. Honest men testified, with perfect confidence and sincerity, to the most absurd impossibilities; while those who thought themselves victims of diabolical influence would actually exhibit, in their corporeal frames, all the appropriate symptoms of the sufferings their imaginations had brought upon them. Great ignorance prevailed in reference to the influences of the body and the mind upon each other. While the imagination was called into a more extensive and energetic action than at any succeeding or previous period, its properties and laws were but little understood: the extent of the connection of the will and the muscular system, the reciprocal influence of the nerves and the fancy, and the strong and universally pervading sympathy between our physical and moral constitutions, were almost wholly unknown. These important subjects, indeed, are but imperfectly understood at the present day.
It may perhaps be affirmed, that the relations of the human mind with the spiritual world will never be understood while we continue in the present stage of existence and mode of being. The error of our ancestors—and it is an error into which men have always been prone to fall, and from which our own times are by no means exempt—was in imagining that their knowledge had extended, in this direction, beyond the boundary fixed unalterably to our researches, while in this corporeal life.