“A fox knows many things, but a hedgehog knows one big thing” – Isaiah Berlin

If we look back toward the beginning of the universe, we can see the fragile nature of existence. If events unfolded differently, life would not exist.

Particles and anti-particles, or matter and anti-matter, were residues of the energy created by the heat of the Big Bang. As the universe cooled, the particles and anti-particles destroyed one another in pairs. If the amounts of matter and anti-matter had been equal, everything would be annihilated, and there would be no life in the universe. There wouldn’t be anything.

There had to be an initial asymmetry, slightly more matter than antimatter, so that after the universe cooled, there would be stars left over. Thus, the universe exists because of a basic dichotomy, between matter and anti-matter.

But is it also true that everything has this dual character? Psychologists and philosophers have ascribed this dualism to a variety of subjects including brains, nature, morality, information, perception, and problem-solving. Does a fundamental division really exist metaphysically, or is this simply an illusion of the mind?

How should we understand the "coincidence of opposites"? Is human psychology truly the result of a tension between opposites? Throughout the book, we will explore these ideas through the perspectives of many different thinkers in history, and see why this critical concept has sowed such deep divisions between people. We will explore to what extent the grand ideas in history can explain modern social phenomena, including increased narcissism, polarization, and naivety.