Living is a balancing act. Ordinary activities like walking, running, or riding a bike require the brain to keep the body in balance. A dancer's poised elegance and a tightrope walker's breathtaking performance are feats of balance. Language abounds with expressions and figures of speech that invoke balance. People fret over work-life balance or try to eat a balanced diet. The concept crops up from politics-checks and balances, the balance of power,...