Socrates, one of the most renowned of the Greek, sages, used and taught as an axiom to his hearers: "Know thyself".
One of the most reliable means of learning to know oneself is the study of temperaments. For if a man is fully cognizant of his temperament, he can learn easily to direct and control himself. If he is able to discern the temperament of others, he can better understand and help them. Temperament then is a fundamental disposition of the soul, which manifests itself whenever an impression is made upon the mind, be that impression caused by thought, by thinking about something, or by representation through the imagination or by external stimuli.