That we are more or less impressionable in our sleep is rendered evident by the facility with which even a sound sleeper is disturbed by the slightest noise: the sparkling of a fire, or the crackling produced by the wick of our night-lamp when coming into contact with the water in the glass, the sting of an insect, the slightest admission of a higher or lower temperature, will occasion a broken sleep and its dreams. It has been remarked that the sense of seeing is more frequently acted upon in dreams than that of hearing, and very seldom do we find our smell and taste under their influence. It is possible that this peculiarity may arise from the greater variety of impressions with which the sight is daily struck, and which memory communicates by association or retransmission. Next to feeling, vision is the first sense brought into relation with external objects. When we hear noises, explosions, tumultuous cries, it is more than probable that our dreams partake of a delirious and morbid nature, or of sensorial or intellectual hallucinations, in which the mind is actually diseased, and our perceptions become erroneous: then we speak loudly to others, and to ourselves. When these hallucinations prevail after sleep, the invasion of mania may be apprehended. Cabanis, in his curious investigations on the mind, has endeavoured to fix the order in which the different parts of our organization go to sleep. First the legs and arms, then the muscles that support the head and back: the first sense that slumbers, according to his notions, is that of sight; then follow in regular succession the senses of taste, smell, hearing, and feeling. The viscera fall asleep one after the other, but with different decrees of soundness. If this doctrine be correct, we may easily conceive the wild and strange inconsistencies of our dreams, during which the waking and the sleeping organs are acting and reacting upon each other. Corporeal sensations and different organic actions frequently attend our dreams; but these may be attributed to our mode of living, or the indulgence in certain unruly desires and conversations. That man and animals dream of the pursuits of the preceding day there can be no doubt: hence the line, Et canis in somnis leporis vestigia latrat. The effects of a heavy meal, more especially a supper, in disturbing our rest, was well known and recorded by ancient physicians: and Crato tells us "that the fittest time to repair to rest is two or three hours after supper, when the meat is then settled in the bottom of the stomach: and 'tis good to lie on the right side first, because at that side the liver doth rest under the stomach, not molesting any way, but heating him as a fire doth a kettle that is put to it. After the first sleep 'tis not amiss to lie upon the left side, that the meat may the better descend; and sometimes again on the belly, but never on the back."