I PROPOSE to describe an extremely curious form of mental alienation which does not often occur, except among subjects whose minds have received a certain degree of culture, and the victims of which are seldom consigned to the asylum. It is an affection the subjects of which nearly always belong to the category of free eccentrics. I refer to the singular perturbation of mind which has been described by the elder Falret as the doubting disease (maladie du doute); by the younger Falret as partial insanity, with dread of the touch (crainte du contact) of exterior objects; by Oscar Berger as Grübelsucht, or the mania for subtilties; and by Legrand du Saulle as the folly of doubt, with delirium of the touch (folie du doute avec délire du toucher).
Waiving for the present the consideration of the tactile element, we might, perhaps, designate this mental state, which is always accompanied by consciousness, by the name which has frequently been given it of "metaphysical delirium." The case is really one of a morbid condition that is variable in its manifestations and which deserves, according to the particular forms in which it exhibits itself, all the names that have been given it. One patient, for example, will doubt everything, even his own existence, and will not be able to fix himself to any formal conviction. Another will manifest, besides this psychological state, a real fear of the contact of exterior objects. Another will feel a constant inclination to split hairs into quarters, and to exhaust all the subtilties of the ancient scholastics upon the most frivolous and trite subjects. All of these conditions, apparently so different, are brought together by one characteristic trait of intellectual restlessness.
"The true basis of this mental disease," says M. J. Valient, in his "De la Folie Morale," "is a general disposition of the intellect to return continually upon the same ideas or the same acts, to feel a continuous necessity for repeating the same words or performing the same actions, without ever satisfying itself, or being convinced even by evidence. I have described certain phenomena of this order under the name of intellectual impulsions. I give a curious example of them. A young collegian, who had previously been very regular in his habits, was present at a party where some of his friends were jesting about the fatal influence attributed to the number thirteen. Suddenly an absurd thought occurred to him that, if thirteen was an unlucky number, it would be deplorable if God were thirteen, space thirteen, infinity thirteen, and eternity thirteen; and, to forefend such a woe, he every instant formulated in his mind an ejaculatory prayer thus conceived: