In Traditional Chinese Medicine,
血 (blood) and
气 (qi, vital energy) are the twin pillars of bodily health - too many illnesses are diagnosed as
血气不足 (blood-qi deficiency). The term jumped from medicine into character description: a
血气方刚 man is one in his prime - full of vigor, courage, and impulsive energy.
论语·季氏 first paired the four characters.
