The proof is by reduction ad absurdum, and reduction ad absurdum, which Euclid loved so much, is one of a mathematician’s finest weapons. It is a far finer gambit than any chess gambit: a chess player may offer the sacrifice of a pawn or even a piece, but a mathematician offers the game.
──G. H. Hardy, A Mathematician's Apology
哈代(Godfrey Harold Hardy, 1877-1947)英國數學家。在一次受訪中有人問哈代,他以為自己對數學最大的貢獻是甚麼?哈代說:他發現拉馬努金。