Nothing physical can exist without an opposite — except Singularity. Everything real is a bonded pair, and the tension between them is what makes it alive.
For anything to be something, it must have two opposite sides.
Opposites Attract. Likes Repel.
Begin with a single law and let everything follow from it. Two things that are alike push apart; two things that are opposite are drawn together. This is not sentiment — it is the same pull that binds a positive charge to a negative one, a north pole to a south, a proton to an electron. Attraction is what opposition does.

Male and Female do not mean man and woman. They mean (+) and (−), dominant and recessive.
Strip the human costume off the pair and you find the machinery underneath. Male and female, dominant and recessive, positive and negative are the same relationship wearing different clothes. Life reaches for its opposite because only a bonded pair can hold together long enough to become something.

The first two pages of this chapter are free. Here are the other twelve.