Temperament, a term used to express the differences in the physical and mental constitutions of individuals, referred from remote antiquity to peculiarities in the quality of the solids and fluids of the body. The ancients believed that the fluids of the body consisted of four humors (corresponding to the four then so-called elements, earth, air, fire, and water), which they named bile, blood, black bile (supposed to come from the spleen), and phlegm or watery fluid (believed to come from the brain); and, if either of these elements was in excess, that it gave rise in the above order to the bilious or choleric, sanguine, melancholic, and phlegmatic temperaments. This view was maintained by physicians to the time of Cullen, who admitted only two temperaments, the sanguine and the melancholic. The sanguine temperament is marked by a predominance of the circulatory system, with a strong and frequent pulse, firm flesh, plump figure, smooth and fair skin, ruddy complexion, soft and light hair, and light eyes; there is great nervous susceptibility, ready memory, lively imagination, cheerfulness, and a love for sensual pleasures; its diseases are generally violent and inflammatory.

In Cullen's melancholic temperament the solids predominate, the figure being less plump and more firm, the hair and eyes black, the skin coarse and dark, the countenance sallow and sad; the disposition is gloomy and the temper suspicious; the manner is slow, grave, cautious, and impassive. Other temperaments as well characterized as the above are the bilious, lymphatic, and ner-vous. The bilious or choleric temperament is marked by a supposed predominance of the biliary system, with strong hard pulse, yellowish brown skin and dark hair, and moderately fleshy body; by violent and easily excited passions, firmness and inflexibility of character, boldness, and perseverance. In the phlegmatic or lymphatic temperament the flesh is soft, the skin pale and flabby, hair light, pulse weak, and the figure rounded, with little expression of countenance or activity of mind and body. The prominent character of the nervous temperament is a great excitability of the nervous system, and the preponderance of the emotions and impulses over the reason and will; the muscles are small and soft, and the form generally slender.