Not only are the mental powers intensified in this state, but the physical energies are unwontedly increased. Horstius relates the case of a young nobleman living in the Citadel of Breslau, who used to steal out of his window during his sleep, muffled up in a cloak, and, by great muscular exertion, ascend the roof of the building where, one night, he tore in pieces a magpie's nest, wrapped up the little ones in his cloak, and then returned to bed; and, on the following morning, related the circumstances as having occurred in a dream, nor could he be persuaded of its reality until the magpies in the cloak were shown to him. In the "Bibliothèque de Médecine" we find the account of a somnambulist who got out of his bed in the middle of the night, and went into a neighboring house which was in ruins, and of which the bare walls, with a few insecure rafters running between them, alone remained; nevertheless he climbed to the top of the wall, and clambered about from one beam to another, without once missing his hold. It is affirmed that somnambulists will maintain their footing in the most perilous situations with perfect safety, so long as they remain in a state of somnambulism; but when they are disturbed or awakened in such positions, they are then taken by surprise, and instantly lose self-possession. A young lady was observed at Dresden walking one night in her sleep upon the roof of a house; an alarm being given, crowds of people assembled in the street, and beds and mattresses were laid upon the ground, in the hope of saving her life in case of her falling. Unconscious of danger, the poor girl advanced to the very edge of the roof, smiling and bowing to the multitude below, and occasionally arranging her hair and her dress. The spectators watched her with great anxiety. After moving along thus unconcernedly for some time, she proceeded toward the window from which she had made her exit. A light had been placed in it by her distressed family; but the moment she approached it, she started, and suddenly awakening, fell into the street, and was killed on the spot. Upon this incident Bellini founded the charming opera of "La Sonnambula."