The fourth section also includes hallucinations that accompany mania; they are often associated with illusions, or alternate with them. Their frequency is almost as great as in monomania, but it is often more difficult to detect them, because maniacs pass from one object to another, are capricious, reply with volubility, and pay no attention to the questions addressed to them. There is a variety of this mania with lying-in women, which is observable in many cases. A fact which is more rare, but which we have likewise noted, is the persistence of this symptom in the last stage of general paralysis. It is probable that hallucinations exist in some degrees of imbecility.

Hallucinations which are exhibited in delirium tremens, drunkenness, after the absorption of narcotics and poisons, are the subjects of the fifth section; we have thought it proper to separate alienation from mental hallucinations, which, linked with the action of these substances, do not really show themselves with the characters of madness, and we have chosen to speak of them under the article Etiology. Delirium tremens, as well as madness from inebriety, has a great influence on the conduct; we have examined each under the triple relation of morality, medicine, and law.

The sixth section comprises hallucinations connected with catalepsy, epilepsy, hysteria, hypochondria, etc.

The hallucinations of nightmare and dreams constitute the seventh section. It is evident that nightmare has points of relation with madness, which are observable in that state. There are also dreams, which are closely analogous to hallucinations. The physiological study of dreams has presented many interesting particulars; it is thus, for instance, that presentiments appear to us explainable in most cases by hallucinations. It must not, however, be thought that presentiments occur only in dreams, and that hallucination always explains them. One case of nocturnal hallucination which is related in this section may throw some light on actions frequently inexplicable. Indeed, we have proved that nocturnal hallucinations have sometimes existed as an epidemic.

There is a singular state of the mind known under the term ecstasy, the phenomena of which have justly attracted the researches of observers. The hallucinations which are one of its distinctive characteristics have induced us to form it into an eighth section. Prolonged concentration of thought on one object is terminated by an ecstatic state of the brain, in which the object is reproduced, and affects the mind as if it were really perceived by the eyes of the body. With this state of the mind may be classed the visions of celebrated men. Their hallucinations had often no influence on their reason, particularly when they were united to the general belief of the time, and when they occurred during the ecstasy that we have termed physiological. Ecstasy has several times been noticed in children; in catalepsy, hysteria, overwrought mysticism, and mental alienation.

Certain special phenomena, such as premonition, clairvoyance, second-sight, magnetism, and somnambulism, appear to us related to ecstasy. The effect of cold has also occasioned this nervous state. Ecstasy has been observed in all climates; and even lately has appeared among several thousand persons in Sweden. The hallucinations observed in these different nervous states, and especially in somnambulism, may cause acts involving great responsibility.

The ninth section of the classification comprehends febrile complaints, acute, chronic, and other inflammations, and certain atmospheric states. Amongst the diseases in which this symptom has been most frequent, we will notice acute delirium, which has been observed in madhouses, fever, attacks of the brain, parenchymatous inflammations, typhus and typhoid fevers, intermittent fevers, gout, chlorosis, pellagra, hectic diseases, syncope, asphyxia, lethargy, convalescence, etc. Atmospheric influences appear to have frequently caused this symptom.

Finally, in the last section we have exhibited the hallucinations and epidemic illusions of which we have elsewhere spoken.

Such is the circle in which we have collected the facts relative to hallucinations which have come under our notice; large as it may be, we believe that the arrangement is such as to enable any one to comprehend the whole.

By the numerous divisions that we have established, it will be perceived that hallucinations have different causes. The two great moral and physical categories, indicated at the commencement of this chapter, are the leading points whence emanate a multitude of second causes. As, in mental alienation, dominant ideas have a great influence on hallucinations, so, during the reign of demonology, sorcery, magic, lycanthropy, and vampirism, men everywhere saw devils, sorcerers, men-wolves, vampires, etc. With different degrees of civilization, the character of hallucination varies. With the Greeks, it was exhibited in the form of pans, fawns, naiades. With the Romans, it took the aspect of genii. In the Middle Ages, it was manifested in the form of angels, saints, and devils. In our time, all possible combinations of thought form the basis. When hallucinations are produced by physical causes, they may be referred more or less to each of these; but, as we have already announced them in several preceding sections, we will abstain from repetition.

Correctly speaking, the preceding paragraph has reference only to the secondary causes of hallucinations; it was necessary to consider them on higher grounds, which we have endeavored to do in a chapter in which they are regarded in a psychological, historical, moral, and religious view. In the early part of this chapter, we have shown that the first causes of hallucinations must be sought for in the violation of some great principle, in the erroneous direction of ideas, and by consequence in the abnormal production of their perceptible signs. After having entered on more extended considerations of the nature of ideas, their division, the principal operations of the mind which are brought into play in hallucinations, we have shown that these should often be considered as almost a normal fact, to which we have already alluded in speaking of physiological ecstasy. This mode of treating the subject of hallucinations has enabled us to explain how so many celebrated men have been thus affected, without on that account being insane. The examples of Loyola, Luther, and Joan of Arc offer themselves at once as decided demonstrations in favor of this opinion.