_Delirium of Disease._--The ordinary _delirium of disease_ is essentially of the same nature with that now described, differing rather in its origin, or producing cause, than in its effects. It comes on often in much the same way; increased mental activity shows itself; attention is fixed with difficulty; strange images, and trains of thought at once singular and uncontrolled by the will, come and go; the mind at last is possessed by them and loses all control over its own movements. Every thing now, which the mind conceives, assumes the form of reality. It has no longer conceptions but perceptions. Figures move along the walls and occupy the room. They are as really _seen_, that is, the _sensation_ is the same, as in any case of healthy and actual vision; only the effect is wrought from within outward, from the sensorium to the optic nerve and retina, instead of the reverse, as in actual vision. Voices are heard also, and various sounds, in the same manner; the producing cause acting from within outward, and not from without inward. _Differs from Dreaming._--This state differs from dreaming in that the subject is not necessarily asleep, and that it involves a greater and more serious disorder of the faculties, as well as of longer continuance. The illusions are perhaps also more decided, and more vividly conceived as external and real entities. Like dreams, and unlike the conceptions of the magnetic state, these ideas and illusions may be subsequently recalled, and in many cases are so; the mind, however, finding it difficult still to believe that they were _fictions_, and not actual occurrences. In dreaming, the things which we seem to see and hear are changes produced in the sensorium by cerebral or other influences. In delirium, the sensorium itself is disordered and produces false appearances, spectres, etc. _Mania._--That form of disordered mental action termed _mania_, differs from that already described in that, along with the derangement of the intellect, there is more or less emotional disorder. The patient is strongly excited on any thing that at all rouses the feelings. There may be much or little intellectual derangement accompanying this excitement. The two forms, in fact, pass into each by a succession of almost indefinable links. The main element is the same in each, _i. e._, loss of voluntary control over the thoughts and feelings. Each is produced by physical causes, and is of transient duration.