Victory goes to the player who makes the next-to-last mistake. (Chessmaster Savielly Grigorievitch Tartakower)

The difference between ‘involvement’ and ‘commitment’ is like an eggs-and-ham breakfast: the chicken was ‘involved’ – the pig was ‘committed’. (unknown)

Each problem that I solved became a rule which served afterwards to solve other problems. (Rene Descartes, Discours de la Methode)