As some very erroneous notions have been entertained concerning the state of the brain, and more especially respecting its consistence in maniacal disorders, I have been induced to examine that viscus in those who have died insane, and have endeavoured with accuracy to report the appearances. It seemed proper to give some general history of these cases; perhaps the account which has been related of their erroneous opinions might have been spared, yet some friends whom I consulted expressed a wish that they had been more copiously detailed. Of the difficulty of enumerating the remote causes of the disease I have been fully aware, and have mentioned but few, that I might be accused of the fewer mistakes. The prognosis contains some facts which, as far as I am informed, have not hitherto been made known, and appear to me of sufficient importance to be communicated to the public. As it is my intention at some future period to attempt a more finished performance on the subject of Insanity, I shall feel grateful for any hints or observations, with which the kindness of professional gentlemen may supply me. BETHLEM-HOSPITAL, MARCH 14, 1798. OBSERVATIONS ON INSANITY. CHAP. I. Readers in general require a definition of the subject, which an author proposes to treat of; it is the duty therefore of every writer, to define, as clearly as he is able, that which he professes to elucidate. A definition of a disease, should be a concentrated history, a selection of its prominent features and discriminative symptoms. Of the definitions which have been given of this disease, some appear too contracted; and others not sufficiently precise. Dr. Mead, after having treated largely upon the subject, concludes, "That this disease consists entirely in the strength of imagination." If the disease consisted entirely in the strength of imagination, the imagination ought to be equally strong upon all subjects, which upon accurate observation is not found to be the case. Had Dr. Mead stated, that, together with this increased strength of imagination, there existed an enfeebled state of the judgment, his definition would have been more correct. The strength, or increase of any power of the mind, cannot constitute a disease of it; strength of memory, has never been suspected to produce derangement of intellect; neither is it conceived, that great vigour of judgment can operate in any such manner; on the contrary it will readily be granted, that imbecility of memory must create confusion, by obstructing the action of the other powers of the mind; and that if the judgment be impaired, a man must necessarily speak, and generally act, in a very incorrect and ridiculous manner.