The term comes from a story
in Hanfeizi. In the story, mao (矛) is a spear that is said to be able to pierce
anything; dun (盾) is a shield that is said to be able to be pierced by
nothing. Mao and dun are a paradox to each other, so a person cannot affirm both
propositions at the same time. Later, the term came to mean “contradiction,” or “inconsistency between speech and action.”
This term refers to two things that are mutually opposite to but complementing each other and that they mutually transform between them. Everything is an antithesis to something else. Both antithetic sides are opposite to each other. Therefore there is mutual exclusion between them, such as you and wu, long and short, high and low, good and bad, and beautiful and ugly. On the other hand, the nature or the identity of a thing is established due to something antithetic to it. The two opposing sides can transform into each other under certain conditions. This concept emerged in the pre-Qin period. In The History of the Han Dynasty written by Ban Gu(32-92), the idea was first defined as “two things being both opposite and complementary.”
The motion of Dao is to transform into the opposite or return to the original state. This concept was proposed by Laozi. Laozi believed that Dao is the fundamental rule of motion and change of things. The essence of this rule is “return,” which has two different implications. One indicates the contrary and opposite, namely, a thing in motion may transform into its opposite. The other suggests returning, meaning that a thing eventually returns to its initial state. This concept embodies the profound understanding of Laozi and Daoist scholars about the rule governing the motion of things.