_Defects of Memory--Amnesia._--The cases given just above, where the failure of speech was seen to be due to the loss of certain memories of words, illustrate also a series of mental defects, which are classed together as Amnesias. Any failure in memory, except the normal lapses which we call forgetfulness, is included under this term. Just as the loss of word memories occasions inability to speak, so that of other sorts of memories occasions other functional disturbances. A patient may forget objects, and so not know how to use his penknife or to put on his shoes. He may forget events, and so give false witness as to the past. One may forget himself also, and so have, in some degree, a different character, as is seen, in an exaggerated way, in persons who have so-called Dual Personality. These patients suddenly fall into a secondary state, in which they forget all the events of their ordinary lives, but remember all the events of the earlier periods of the secondary personality. This state may be described as "general" amnesia, in contrast to the "partial" amnesia of the other cases given, in which only particular classes of memories are impaired. The impairment of memory with advancing years also illustrates both "general" and "partial" Amnesia. The old man loses his memory of names, then of other words, then of events, and so gradually becomes incapable of much retention of any sort. _Defects of Will--Aboulia._--A few words may suffice to characterize the great class of mental defects which arise on the side of action. All inability to perform intentional acts is called Aboulia, or lack of Will. Certain defects of speech mentioned above illustrate this: cases in which the patient knows what he wishes to say and yet can not say it. This is the type of all the "partial" Aboulias. There may be no lack in determination and effort, yet the action may be impossible. But, in contrast with this, there is a more grave defect called "general" Aboulia. Here we find a weakening of resolution, of determination, associated with some lack of self-control showing itself frequently by a certain hesitation or indecision. The patient says: "I can not make up my mind," "I can not decide." In exaggerated cases it becomes a form of mania called "insanity of doubt." The patient stands before a door for an hour hesitating as to whether he can open it or not, or carries to its extreme the experience we all sometimes have of finding it necessary to return again and again to make sure that we have locked the door or shut the draught of the furnace. With these illustrations our notice of mental defects may terminate. The more complex troubles, the various insanities, manias, phobias, etc., can not be briefly described. Moreover, they are still wrapped in the profoundest obscurity. To the psychologist, however, there are certain guiding principles through the maze of facts, and I may state them in conclusion.