Life is a duality. Two polar opposites.
Night, day.
Left, Right.
Back, front.
Good, evil.
White, black.
Yin, yang.
Time, space.
Feminine, Masculine.
Personally I think the patriarchal society we all suffer is due to a massively deep-seated jealousy complex rooted in the fact that women give life. Men cannot, though now that we have a better understanding that you can't have dark with light, I think we may be ready to evolve back to a partnership society.
Doesn't mean it will happen, but there are hopeful signs.