Originally published in 1928, this title attempts to give a short historical outline of the treatment which ‘temperament’ had received at the hands of psychological theory. From the time of Hippocrates ‘temperament’ had figured in philosophical and psychological writings as one of the constituents which determine behaviour. The language in which it had been treated had been vague and obscure, and this, combined with the equally indeterminate associations which were carried over from the speech of everyday life at the time, had contrived to surround the subject with an atmosphere of unreality which was in sharp contrast to the significance of the role assigned to it.