Laughter is a sound of the voice, interrupted and pursued for some continuance. The muscles of the belly, and the diaphragm, are employed in its weaker exertions; but those of the ribs are violently agitated in the stronger; the head and breast are sometimes thrown forward, in order to raise them with the greater ease. The chest remains undisturbed, the cheeks swell, the mouth naturally opens, and the belly becoming depressed, the air issues out with a noise, and which in violent fits continues for some time, and is often repeated; but in more tranquil emotions, although the cheeks swell, the lips remain close, and in some persons dimples are formed near the corners of the mouth. This smile is often an indication of kindness and good-will; it is also often used as a mark of contempt and ridicule. The cheeks are features without any particular motion, and rather seem as an ornament to the face than for the purpose of expression, as may also be said of the chin and temples. The former indeed may be considered in some measure a picture of the mind, from the involuntary paleness and redness with which they are at limes overspread. Blushing proceeds from different passions; being produced from shame, anger, pride, Or joy, while paleness is ever an attendant on fright, fear, and sorrow. These alterations in the colour are entirely involuntary; all the other expressions of the passions are, in some small degree, under control; but blushing and paleness betray our secret thoughts, and we might as well attempt to stop the circulation of our blood, by which they are caused, as to prevent their appearance. The whole head, as well as the features of the face, takes peculiar attitudes from different passions; it bends forward to express humility, shame, or sorrow; it is turned to one side, in languor, or in pity; it is thrown with the chin forward, in arrogance and pride; erect in self-conceit and obstinacy; it is thrown backwards in surprize or astonishment; and combines its motions to the one side and the other, to express contempt, ridicule, anger, and resentment. The parts of the head which give least expression to the face are the ears. These which are immoveable, and make so small an appearance in man, are very distinguishing features in quadrupeds: they serve in them as the principal marks of the passions, and discover their joys or their terrors with tolerable precision. The smallest ears in men are said to be most beautiful; but the largest are found the best for hearing. Some savage nations bore their ears, and so draw down the tips to rest upon their shoulders.