788 THE POPULAR SCIENCE MONTHLY. 



DELUSIONS OF DOUBT. 



By M. B. BILL. 



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 vic- 

 tims 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 

 Grilbelsucht, or the mania for subtilties ; and by Legrand du Saulle as 

 the folly of doubt, with delirium of the touch (folie du doute avec 

 d'elire du toucher). 



Waiving for the present the consideration of the tactile element, 

 we might, perhaps, designate this mental state, which is always accom- 

 panied 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 him- 

 self 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 ujDon the 

 most frivolous and trite subjects. All of these conditions, apparently 

 so different, are brought together by one characteristic trait of intel- 

 lectual 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 thir- 

 teen, and eternity thirteen ; and, to forefend such a woe, he every 

 instant formulated in his mind an ejaculatory prayer thus conceived : 



