In schools sleep-talking is very common; anxious pupils, in their sleep, will frequently repeat a lesson they can not remember when awake. The son of the eminent linguist and commentator, Dr. Adam Clarke, tells us that his father overheard him, in his sleep, repeat a Greek verb which he was endeavoring to learn, and which, the following morning, he was unable to remember. This is a curious fact--he knew his lesson in his sleep, but did not do so when he was awake; the faculty of memory, however, in a state of somnambulism undergoes many singular modifications. Thus, persons who talk in their sleep, may, by conversation, be brought to remember a dream within a dream; and it is very common, in the higher stages of somnambulism, for a person to recollect what happened in the preceding fit, and be unconscious of any interval having elapsed between them. A somnambulist, at Berlin, in one of her paroxysms, wandering in her sleep, was guilty of an indiscretion which she had no recollection of in her waking hours; but, when she again became somnambulic, she communicated all the circumstances to her mother. During the next convalescent interval, they again escaped her memory. The case is related, by Treviranus, of a young student who when he fell asleep began to repeat aloud a continuous and connected dream, which began each night precisely where it left off the preceding night. This reminds us of the story of the drunken porter, who in a fit of intoxication left a parcel at a wrong house: when he became sober he could not recollect where he had left it, but the next time he got drunk he remembered the house, and called and recovered it.