《管子·白心》
和协而返于正中，使形体与精气相保，专一而无二意，这就叫懂得了 道 。
和以反中，形性相葆。一以无贰，是谓知道。
Harmoniously returning to the center, allowing physical form and vital energy to protect each other, being single-minded and without ulterior motives — this is called understanding the Way.