Our greatest spiritual systems testify about interdependent opposites. Taoism has yin and yang; Hinduism has Shiva and Shakti; Kabbalah has its “Pillar of Mercy” (kav yamin) and “Pillar of Severity” (kav smol). Sufis worship God as both transcendent (as-Zahir—’Manifest’) and immanent (al-Batin—’Hidden’).

Everything we know, we know both in-and-of-itself and conditioned by its essential opposite. Duality is built into our bodies: our inhale and exhale, the systole and diastole of our heartbeats, the hemispheres of our brains. It’s built into our psyches: We love and hate, rejoice and grieve simultaneously—often confusing ourselves. Our most fundamental physics is characterized by a phenomenon called wave/particle duality—turns out, everything we’re made of behaves both ways! It’s a puzzle.