_Illustrations of the first._--As to the first of these modifying causes, instances of its operation will probably occur to every one from his own experience. You find yourself on a hard bed, or, it may be, have thrown yourself into some uncomfortable position, and you dream of broken bones or of the rack. The band of your robe buttons tightly about the neck, and you dream of hanging. You have taken a late supper of food highly seasoned and indigestible, and in your dreams a black bear very heavy and huge, quietly seats himself on your chest, or, as a military officer once dreamed, under similar circumstances, the prince of darkness sits cross-legged over your stomach, with the Bunker Hill monument in his lap. The instance related by Mr. Stewart, of the gentleman, who, sleeping with bottles of hot water at his feet, dreamed that he was walking along the burning crater of Mount Ætna, is in point here. Here the bodily sensation of heat upon the soles of the feet suggests the idea of a situation in which such a sensation would be likely to occur, and this idea blending with the sensation which is permanent and real, assumes, also, the character of reality, and the dream shapes itself accordingly. So when a window falls, or some sudden noise is heard, if it do not positively awaken you so far as to make known the real cause, you hear the sound, the sensorium partially aroused, mistakes it, perhaps, for the sound of a gun, and instantly you are in the midst of a battle at sea, or a fight with robbers. To such an extent are our dreams modified by sensible impressions of this sort, that it is possible, by skillful management, to shape and direct, to some extent, at least, the dreams of another as you will. An instance is related of an officer who was made, in this way, in his sleep, to go through with all the minutia of a duel, even to the firing of the pistol which was placed in his hand, at the proper moment, the noise of which awoke him. This was simply an _acted_ dream. _Latent Disease._--Not unfrequently, some physical disorder, incipient or latent, of which we may not be aware in our waking moments, makes itself felt in the state of sleep, when the system is more susceptible of internal impressions, and thus modifies the dreams. In such cases, the dreams may serve as a sort of _index_ of the state of the physical system, and somewhat, doubtless, of the apparently prophetic character of certain dreams may be accounted for in this way.