Changes

''Sublime Book of the Mind's Correspondence with the Nine Supreme Essentials'' ( 太上九要心印妙經 Taishang Jiuyao Xinyin Miaojing ), ''Book of the Mind's Correspondence with the Nine Essentials'' for short, is a Daoist book on [[Inner Alchemy ]] ( 內丹 Neidan ) compiled by Zhang Guo of the Tang dynasty. The book divides inner alchemy into three categories and regards the great nine-cycle elixir as the first-rate category. It holds that in the process of making elixirs, each of the nine cycles has its own center, so there are nine essentials.