Huangdi Neijing
The Sasang" constitutional medicine (Hangul: 사상의학. Hanja: 四象醫學) or Sasang" typology is a typological constitution medicine of Traditional Korean medicine. It was systematized by Yi Je-ma in his book "Longevity and Life Preservation in Eastern Medicine" (東醫壽世保元, 동의수세보원) in 1894. It divides people into four body types based on their biopsychosocial traits. The classification was derived from the five body types of Traditional Chinese medicine described in an ancient Chinese medical book Lingshu Jing of Huangdi Neijing.