Marriage is not something that can be accomplished all at once; it has to be constantly reaccomplished. A couple must never indulge in idle tranquility with the remark: "The game is won; let's relax." The game is never won. The chances of life are such that anything is possible. Remember what the dangers are for both sexes in middle age. A successful marriage is an edifice that must be rebuilt every day.

Un Art de Vivre (The Art of Living) (1939) - The Art of Marriage