The Heart of Serenity Classic 太上老君清静心经

The author is unknown. It was presumably compiled during the Tang Dynasty. Consisting of one volume, it is included in the Taiqing Section of The Daozang.

Its full text is also recorded in Volume 17 of Yunji Qiqian (Seven Bamboo Tablets of the Cloudy Satchel). With only over 600 characters, the content is roughly similar to Taishang Laojun Says the Scripture of Constant Purity and Wonder. Its core purport takes purity and tranquility as the fundamental principle, absorbs the Buddhist thought of emptiness and stillness, and clarifies the subtlety of Taoist purity, tranquility, and non-action. It holds that the restlessness of the human mind is all due to the entanglement of desires. If there are no desires, the mind will naturally be quiet and the spirit will not be disturbed, thus achieving constant purity and tranquility; with constant purity and tranquility, one can unite one’s essence with the Dao.

A seven-character Buddhist gatha is appended at the end of the text.