Temperament is a term which has been employed in Physiology ever since the time of Galen, to designate certain physical and mental characteristics presented by different persons. A fourfold classification was long universal, doubtless based on the old idea of four corporeal elements (see MEDICINE, Vol. VII. p. 116). But the two generally regarded as fundamental are the sanguine and the melancholic, the phlegmatic being a degree or modification of the sanguineous, and the choleric of the melancholic.
Some writers recognise a nervous temperament, in which the predominating characteristic is a great excitability of the nervous system, and an undue predominance of the emotional impulses—a temperament always associated with the sanguineous or the melancholic. The names of the jovial, mercurial, and saturnine temperaments are reflections of Astrology (q.v., Vol. I. p. 525). The artistic temperament is also a very current phrase. In both sexes the characteristics of the temperaments are far less manifest in old age than in earlier life. The different temperaments often merge so gradually into one another that very often it would be extremely difficult to decide to which variety any special case belongs.