Tao can be extraordinary (constant), which is a famous saying in Tao Te Ching, which is different from I Ching.

For example, the Book of Changes: Tai Chi gives birth to two instruments, two instruments give birth to four elephants, and four elephants give birth to eight diagrams, eight, eight and sixty-four hexagrams. And Tao Te Ching: Tao gives birth to one, two, three and everything.

Here often refers to the Book of Changes. Extraordinary Tao refers to something different from the Book of Changes.

Tao can be said: Tao can be described, described and spoken.

Extraordinary way: different from I ching.