There is nothing in Tao, and life comes from nothing. Tao gives birth to one, and "one" represents space, and space is the carrier of yin and yang. "Two" stands for Yin and Yang. "Three" stands for harmony between Yin and Yang. "Everything" represents everything in the material world.
Tao is unique. The Tao itself contains yin and yang, which intersect to form a balanced state, in which everything is produced.