“A boxer derives the greatest advantage from his sparring partner…” — Epictetus, 50–135 AD Hands up. Chin tucked. Knees bent. The bell rings, and both boxers meet in the center and circle. Red throws out three jabs, feints a fourth, and—BANG—lands a right hand on Blue down the center. This wasn’t Blue’s first day and despite his solid defense in front of the mirror, he feels the pressure.