For every action there is an equal and opposite reaction. Newton's Third Law of Motion. The fundamental, universal and only principle of Taoism. The value of unity is two. Yin and yang. Central Equilibrium: balance of opposites. Integrity is balance – harmony. Being and becoming. Station and motion. Identity and difference. Sameness and change. Equilibrium and disequilibrium. Parsed and integrated, at the same time, with the same impulse, the same spirit. Eodem spiritu.