Understanding Reality (Chinese Wu Chen P'ien) is one of the basic classics of Taoist spiritual alchemy as practiced in the Complete Reality (Ch'uan-chen) school of Taoism. Writing in the year 1841, the Taoist Chu Chung-t'ang described its status within the tradition in these terms: 11 Wei Po-yang of the Eastern Han dynasty (23-220 C.E.) first revealed the celestial mechanism and expounded its esoteric truths, composing the Ts'an T'ung Ch'i ... In the Sung dynasty (960-1279) Chang Tzu-yang composed the Wu Chen P'ien. Both texts are perennial guides to the study of the Tao."