The Qingjing Jing, Classic of Constant Purity and Stillness, is roughly four hundred characters and is attributed by tradition to Laozi via a Tang-era revelation. It teaches that the Dao has no fixed form, name or intention yet produces and moves everything; that the human spirit loves purity but the mind disturbs it, and the mind loves stillness but desires pull at it; and that eliminating desire settles the mind, which settles the spirit. It then describes progressively letting go of the perception of self, of others, of things. Its practical importance is disproportionate to its length: it is chanted in the daily morning liturgy in Quanzhen temples, is one of the first texts a novice memorises, and is short enough that a great many laypeople know it entirely by heart and recite it while walking or working. If one wanted a single text that Taoist clergy actually have in their heads, this rather than the Daodejing is the candidate.