If you look at the Taoist symbol of Yin Yang, you see that there is a seed of one in the other. You will also notice that it is in constant motion, flowing from one to the other, as life should be - balanced!
Yin yang are not opposing forces (dualities), but complementary opposites, unseen (hidden, feminine) and seen (manifest, masculine), that interact within a greater whole, as part of a dynamic system. Everything has both yin and yang aspects as light cannot exist without darkness and vice-versa, but either of these aspects may manifest more strongly in particular objects, and may ebb or flow over time.
The Sun is yang while the Moon is yin.
Female is Yin while Man is Yang.
Mountain is
Yin while the river is Yang.
Intuitive is Yin while Logical is Yang.