Mengzi (孟子) regarded Xing (性) as perfect and sole reality. This thought means to unify man's naturality and existence.
And, he asserted that the essence of a man is man's Xin (心). But, the meaning of that is based on the thought of Tian (天). On the other side, he makes much of Haoran-zhi-qi (浩然之気). It Qi (気) is pass through man's body and the Cosmos. The reasonabuly, man is able to return to Tian (天) through the Haoran-zhi-qi (浩然之気). Man's mind and body are based on Tian (天). So, he thinks man is a creature that a mind and a body are unified.