 The leading themes revolve around the nature of Tao and how to attain it . Tao is said to be ineffable , and accomplishing great things through small means . Ancient commentaries on the Tao Te Ching are important texts in their own right . Perhaps the oldest one , the Heshang Gong commentary , was most likely written in the 2nd century CE . Other important commentaries include the one from Wang Bi and the Xiang 'er . 
