Abstract
This treatise is written in order to solve the important contradiction between the two theories; in oriental medicine psychological function is responsible for heart, but in western one it is responsible for brain. So we take the methods of studying in the aspects of morphological characteristics(MC) and visceral manifestation theory(VMT, 藏象論) and others about two organs-heart and brain. Brain(頭腦) is preferred to understand as a structure which is manifesting mental activity of heart. So the brain can be named with external heart(外心) corresponding to the relation of kidney(外 and external kidney. Saying conversely, the nutritional foundation of the mental function is the blood of heart, but the enlightening and insightful features of mentality make it's own residence move to the organ in the uppermost and positive site, that is head. And the close relationships on mental functions between heart and brain were discussed in various aspects, like investigation on east and west etymological literature, or Jiu gong and Taoist theory as well as Me and VMT, These understandings can make us know about the pathology of brain by itself. It has deep relations with heart fire and heart blood and kidney essence, and gastrointestinal function and liver with lung additionally. In another point, it makes the highly complicated psychological functions to be explained free from body relatively, and so can do a role in the complement of the strict 5 viscera theory.