Whether such deceptions of sense are to be regarded as morbid or not opinions differ. Many psychiatrists speak of hallucinations, and consider them compatible with complete health. Others hold that they are always symptoms of mental disorder. Hagen * occupies a peculiar position on this question, for he takes hallucinations to be invariably morbid symptoms, yet not symptoms of mental disease. This is connected with his theory that hallucination is a phenomenon of convulsion of certain blood vessels which I cannot here further set forth.

There is a quite arbitrary separation of psychical and somatic conditions at the bottom of this view. What Hagen means is, that the cause, or somatic concomitant, of the hallucination is a convulsion. It is presumable that every mental process whatever has a somatic concomitant, or “cause,” in the organic vehicle of the soul. Hallucinations may have different somatic concomitants from other mental processes, but they cannot be supposed to be peculiar in merely having somatic concomitants. There are some diseases of the brain which are accompanied by no symptoms of derangement of the mind, and are therefore exclusively somatic diseases. But just as soon as the stimulation of a path of sense enters into a psychical metamorphosis, we have to do with a mental process. If this is morbid, we have to do with a symptom of mental disease.

That which determines Hagen to pronounce hallucination under all circumstances to be a proof of a morbid state is its relative infrequency. “Hallucination is in every case a. condition departing from the norm.” But if everything which “departs from the norm” is to be called morbid, then we return to the proposition that genius is morbid, since it “departs from the norm “; for the “normal” man is a tradesman and no “genius.” But I can only meet Hagen with his own maxim, “Quod sola affirmatione affirmatur, sola negatione negatur.”

It is a fact of daily observation that hallucinations can be produced by suggestion, and that not only in hypnosis but in the ordinary condition. If a woman who has never been electrified, and is therefore somewhat nervous, has the electrodes of a galvanic battery placed upon her head without the circuit being closed, while the faradic apparatus is caused to sound, she will not seldom imagine she feels the current distinctly, and perhaps complain that it is too strong. Though there is no current, the woman is positive she feels it. Every inward excitation, especially every emotion, favours such deceptions.

A timid or superstitious person is liable, in crossing a churchyard at night, to see figures, hear voices, etc. These deceptions may be of the class of illusions, shadows of trees being taken for ghosts, and the noise of the foliage for spiritual voices; or they may be pure hallucinations, the pseudo-perceptions not being formed by any outward sensations. An interesting case is described by H. Moore :