The fundamental error into which many physicians have fallen consists in the assumption that catalepsy is, _per se_, a disease. It must be said, however, to the credit of the profession, that no one pretends to understand it. Most medical writers confess that if it is a disease, it is one of which the pathology is but little understood by the profession, and they aver that morbid anatomy throws no light upon it whatever. In fact, some well-known writers have doubted its existence, and have attributed the recorded cases to gross imposture. It is, however, generally held to be a functional nervous disorder; but the tendency of modern investigation is in the direction of its psychic aspects, and moral means are now largely employed in its treatment by the best physicians. The truth appears to be that catalepsy is not a disease in any proper sense of the word. The most that can be said is that it may be considered a symptom of certain diseases. That is to say, inasmuch as it commonly attacks those who are suffering from certain nervous disorders, it might be said to be a symptom indicating the presence of such disorders. But, I repeat, it is not a disease _per se_; and one prominent medical authority goes so far as to admit that "in itself catalepsy is never fatal." He might have gone further, and said that other diseases are rarely fatal when catalepsy supervenes. Catalepsy belongs exclusively to the domain of hypnotism. I employ this term in the broadest significance of its Greek radix; for no matter how the condition is induced, it is purely a sleep of the objective senses, a suspension of the vital functions, a rest of all the vital organs. It can be induced in perfectly healthy persons by the hypnotic processes on the one hand, or, on the other, it may supervene after a long period of illness or nervous exhaustion. In both cases the phenomenon is the same; and when the patient is intelligently treated, the effect is always salutary. It is, in the highest sense of the phrase, a manifestation of the _vis conservatrix naturæ_; it is, of a truth, "tired nature's sweet restorer, balmy sleep."