Geldings and mares neigh less frequently than horses. Their voices are not so strong, but much more shrill. In all horses we may distinguish five kinds of neighing, relative to different passions; in the neigh of joy the voice begins and ends with sharp tones; the horse kicks up at the same time, but without attempting to strike. In the neigh of desire, whether of love or attachment, the horse does not kick, and the voice is dragged to a great length, and ends with a deep sound. The neigh of anger, during which the horse kicks violently with his foot, is short and sharp; that of fear, during which he kicks also, is scarcely longer than that of anger, the voice is hoarse and grave, and seems as if it came from the nostrils only. This neigh is something like the roaring of a lion. That of pain is more like groaning, or breathing with oppression, than of neighing; it is in a grave tone of voice, and follows the alternatives of respiration. It has also been remarked, that horses which neigh frequently from joy or desire, are the best and most generous. Horses, in general, have the voice stronger than mares and geldings; from the birth the male has the voice stronger than the female. At two years, or two years and a half, which is the age of puberty, the voice of males and females, as in mankind, and other animals, becomes much more strong and deep. When the horse is impassioned with love he shews his teeth, and seems to laugh; he shews them also when he is angry, and would bite. He sometimes puts out his tongue to lick, but less frequently than the ox, who, notwithstanding, is less sensible to caresses. The horse remembers ill treatment much longer, and is sooner dispirited, than the ox. His natural spirit and courage induce him to make every effort, but when he finds more is expected from him than he is able to perform, he grows angry, and will not endeavour at all; instead of which, the ox, who is slow and idle, seldom exerts his utmost, and is not therefore easily dejected. The horse sleeps much less than man, for when he is in health he does not rest more than two or three hours together; he then gets up to eat. When he has been much fatigued he lies down a second time, after having eat; but in the whole he does not sleep more than three or four hours in the twenty-four. There are even some horses who never lie down, but sleep standing, which is sometimes the case even with those who do lie down. It has also been remarked, that geldings sleep oftener and longer than horses.