It is essential for the production of hallucinations that certain faculties, amongst which imagination holds an important place, should be brought into play. But when these faculties are entirely extinct, as in the last degree of madness, or when they have never been developed, as in idiotism and cretinism, these errors of the senses cannot take place.

A difference ought to be recognized in the imbecile whose mind is not totally destroyed; who, for example, has memory, is teachable, exhibits gratitude, evinces fear, is sometimes revengeful, etc. It may easily be understood, that where these faculties exist, in howsoever limited a degree, hallucinations may occur. To us there seems no doubt that many censurable, even culpable acts, have been committed by imbeciles who have had hallucinations and illusions. Undoubtedly, the imbecile insane are credulous, and this disposition of mind makes them docile instruments in the hands of adroit rogues; but an examination of their faculties proves that they may be led away by hallucinations.

Recapitulation. - The imbecile who has the use of several faculties, may have hallucinations and illusions. The complete absence of mind in idiots and cretins makes the production of hallucinations impossible in their case.