• Getting people to fight by letting the force of momentum work is like rolling logs and rocks. Logs and rocks are still when in a secure place, but roll on an incline; they remain stationary if square, they roll if round. Therefore, when people are skillfully led into battle, the momentum is like that of round rocks rolling down a high mountain - this is force.

    Sunzi, Sun-Tzu, Thomas Cleary (1998). “The illustrated art of war”, Shambhala Pubns