PREFACE.
Thediseases which form the subject of the present investigation afford a deep insight into the workings of the human mind in a state of society. They are a portion of history, and will never return in the form in which they are there recorded; but they expose a vulnerable part of man—the instinct of imitation—and are therefore very nearly connected with human life in the aggregate. It appeared worth while to describe diseases which are propagated on the beams of light—on the wings of thought; which convulse the mind by the excitement of the senses, and wonderfully affect the nerves, the media of its will and of its feelings. It seemed worth while to attempt to place these disorders between the epidemics of a less refined origin, which affect the body more than the soul, and all those passions and emotions which border on the vast domain of disease, ready at every moment to pass the boundary. Should we be able to deduce from the grave facts of history here developed, a convincing proof that the human race, amidst the creation which surrounds it, moves in body and soul as an individual whole, the Author might hope that he had approached nearer to his ideal of a grand comprehension of diseases in time and space, and be encouraged, by the co-operation of contemporaries, zealous in the search of truth, to proceed along the path which he has already entered, in prosecuting the investigation.