Visions are appearances to the mind's eye without a corresponding reality. Of the hallucinations of the insane it is necessary to say but little, as there is no doubt as to their nature and source. Generally the insane think them to be true perceptions, and endeavor to conform their conduct to them. Yet in some instances, and very often in the beginning of insanity, they admit them to be morbid and contend against them.

A question of deeper interest, and of closer relation to the subjects treated in this volume, is whether subjective visions are possible to the sane; and, if so, whether they arc at all common, and liable to occur as isolated circumstances. On a full survey of the subject, both these questions must be answered in the affirmative. To say nothing of the visions produced by alcohol, opium, hashish, fever, blows upon the head, prolonged abstinence, deep anxiety, or those which precede attacks of epilepsy or of apoplexy, it is certain that hallucinations often arise without assignable cause or subsequent effect; and the subjects of them demonstrate their sanity by recognizing the unreal character of their perceptions.

Griesinger, one of the most eminent and discriminating writers on mental diseases, says: "Nothing would be more erroneous than to consider a man to be mentally diseased because he had hallucinations. The most extended experience shows rather that such phenomena occur in the lives of very distinguished and highly intellectual men, of the most different dispositions and various casts of mind, but especially in those of warm and powerful imagination." In illustration he speaks of Tasso, who, in the presence of Manco, carried on a long conversation with his protecting spirit; and of Goethe's well-known blue-gray vision, and his ideal flowers with their curious buds. He speaks briefly also of the hallucinations of Sir Walter Scott, Jean Paul, Benvenuto Cellini, Spinoza, Pascal; of Van Helmont, who saw his own soul in the form of a light with a human countenance; of Andral, the great physician, who experienced an hallucination of sight; and of Leuret, an investigator, thinker, and writer whose testimony may be implicitly trusted, who, in his "Fragments of Psychology," gives an account of a phantasm of hearing which he experienced.

A. Brierre de Boismont divided hallucinations that are compatible with sanity into two kinds — those which are corrected by the understanding, and those which, on account of superstition, sluggishness of thought, love of the marvelous, inability to interpret them correctly, or because the emotions which they excite make calm consideration impossible, are not corrected. The cases which he adduces are numerous and striking. One is that of Talma, who, when he trod the stage, could by the force of his will make all the brilliant dresses of his numerous audience disappear and substitute skeletons for the living characters. When he had thus filled the theater with these singular spectators, his emotions were such as to give to his playing a force which produced the most striking effects. The case of an intelligent lady who would see a robber enter her chamber and conceal himself under her bed is in point. Though the spectacle produced violent palpitation of the heart and universal trembling, she was aware of its falsity, and after some moments her judgment and reason would triumph so that she could approach the bed and examine it without fear.

Another case was communicated by a physician of acknowledged reputation to Sir Walter Scott. The first hallucination was that of the presence of a great cat. After a few months the cat disappeared, and a phantom of a higher grade took its place — that of a gentleman usher dressed as though he was in the service of a lord lieutenant, or of some great functionary of the Church. But after some months he disappeared, and a phantom horrible and distressing—a skeleton—appeared. The fact of these visions was concealed by the subject of them, who was an importaut officer in a department of justice, for several years. Though he knew that they were of subjective origin, they wore him out, and he died a victim to the agony in which his life was passed.

Dr. Abercrombie gives a case of a man who had been all his life beset by hallucinations: when he met a friend in the street, he was uncertain whether he was a real person or a phantom, but by paying close attention he could distinguish between them. Dr. Abercrombie declares that he was at the time of writing in good health, of a clear intellect, and occupied in business.

Many forcible instances, the most valuable of which are those personally attested by Boismont, or by the authorities whom he quotes, are given where the mind was sane, though the hallucinations were not corrected by it. It must not be supposed that these hallucinations of the sane are confined to persons of distinction, sedentary habits, or poetic temperaments. Many have had once or twice in their lives spectral illusions, or instances of hallucination ; and among plain men, mechanics, laborers, and the peasantry of all nations, they are very common. Griesinger, after giving a list of distinguished men who, though sane, had hallucinations, says: "Judging from what we have heard and observed on this subject, hallucinations doubtless occur also in men of very average minds, not as rare but as frequently overlooked phenomena".

I suggested, more than twenty years ago, the importance of a census upon a large scale of hallucinations of the sane. Within the last four or five years a somewhat systematic attempt has been made on both sides of the Atlantic. The results so far as tabulated show meager returns, though recently the Society of Psychical Research has given increased attention to the matter. Some of the most fruitful fields for such a census appear to have been neglected.

Down to within a few years a large proportion, if not a majority, of the converts in revivals in evangelical denominations, in the course of their religious exercises, experienced transient hallucinations, some of which were grotesque, some coherent, and others sublime. Thus, a business man who had fasted, prayed, and lost sleep for several days, was in his barn attending to his horses, when he saw before him in broad daylight a wheel revolving rapidly. It was about the size of a cart-wheel, and emitted radiant sparks and streams of light of various colors. He said to himself, "Am I dreaming, or have I lost my senses?" Recognizing the different objects around him, he concluded that he was in his right mind, and fixed his eyes upon the wheel, which still whirled with inconceivable speed. Suddenly he discerned standing upright and immovable in the midst of it, unaffected by the motion of the rim, the form of the Saviour, who pronounced his sins forgiven. The hallucination continued some minutes. He believed it a divine evidence of conversion; its origin was undoubtedly subjective.