illusions.—An illusion is a sense-per ception having an objective basis, but falsely translated to the consciousness. It is a faulty conception of an actual sense-impression. For example, when an undefined noise is heard as spoken language; when a fog is taken for the smoke of a burning city; when the pres sure of a closely-fitting collar gives the impression and causes the feeling of strangulation,—these are illusions.
Delusions.—Delusions are false con ceptions and judgments. Wood's defini tion of a delusion—the best and clearest ever formulated—is: "A faulty belief concerning a subject capable of physical demonstration out of which the person cannot be reasoned by adequate methods for the time being." According to this definition all faulty beliefs or false judgments are not de lusions. A faulty belief may be a delu sion in one person and not in another. It is largely a matter of education, or of environment. Thus, certain political views or religious beliefs held by large numbers of the people appear to others as delusions. Persons without a physical or mathematical education may believe that perpetual motion and squaring the circle are possible. Physicists and mathe maticians know that they are not pos sible. The contrary belief is not a delu sion, but simply ignorance. The preva lent belief among some communities in the North during the late war between the States, that all rebels had horns, was similarly ignorance and not a delusion, although the writer knew persons who held the belief.
A difference is made between insane and sane hallucinations and delusions.
The former are said to dominate the life and acts of the subject, while in the life and conduct of the latter the hallucina tions and delusions are merely incidental.
The distinction is an arbitrary and in definite one.
[Shakespeare had apparently a clear notion of the difference. In "Macbeth," in the dagger scene, the hallucination is evidently recognized by the chief actor as a false sense-impression, since he asks: "Art thou but a dagger of the mind, a false creation proceeding from the heat oppressed brain?" In the banquet-scene, on the contrary, all doubt of the reality of the vision has ceased when he ad dresses Banquo's apparition as if there were no doubt of its real presence.
GEORGE H. 11011E.] Delusions are divided into expansive delusions, or delusions of grandeur;: de pressive delusions, or delusions of debase ment; delusions of persecution, and re ligious and sexual delusions. The delu sions of grandeur and of debasement are the fundamental varieties. The others are mere modifications of them. Perse cutory, religious, and sexual delusions are based upon some delusion of exalted or debased personality. This an insane person regards himself as persecuted be cause he is the offspring of royalty, illegally kept out of his rightful sphere; another is the saviour of mankind, but, like the Son of God, he has come unto his own and his own have known him not; another has boundless sexual power, and can generate a higher and nobler class of beings, but his enemies destroy or fraudulently substitute some inferior being in the place of the paragon. In all these phases of delusive belief the grandiose character is maintained, and the idea of persecution is merely a fur ther development thereof.
Delusions of grandeur are present in general paresis, in which disease they have long been regarded as characteristic. They are also an essential element in paranoia, in which persecutory delusions are an outgrowth of them. In melan cholia, delusions of debasement are often characteristic. In mania delusions of grandeur are often transitory and vary ing; in general paresis they are ex tremely extravagant, and in paranoia they are fixed and in a sense logical.
Case of systematic delirium of grand eur without noticeable lowering of the intellect. G. Baliet and Arnaud (An nales Medico-psychol., Mar., Apr., '95).
Delusions of debasement or unworthi ness are common in melancholia; they are rare in paranoia.
Delusions of persecution are character istic of paranoia. In this form of in sanity they are closely connected with hallucinations of hearing, smell and taste; indeed, delusions in the majority of cases are outgrowths of hallucinations. Persecutory delusions are extremely dangerous symptoms. Under the influ ence of such delusions most of the acts of violence of the insane are com mitted.