Men are moved by two levers only: fear and self interest.

A cold and partly accurate account of motivation. Fear and advantage do explain a great deal of behaviour, especially at scale, and anybody designing a system who ignores them will be surprised by what people actually do. The account is also incomplete, since it cannot explain the parent, the volunteer, or the person who tells the truth at cost.

Use it as a diagnostic without adopting it as a creed. When somebody’s behaviour puzzles you, check the two levers first, because the answer is often plainly there. Then look for the third thing, which is what most people are actually living for.