There is no permanent equilibrium in human affairs. Faith, wisdom, and art allow one to attain it for a time; then outside influences and the souls' passions destroy it, and one must climb the rock again in he same manner. This vacillation round a fixed point is life, and the certainty that such a point exists is happiness. As the most ardent love, of one analyses its separate moments, is made up of innumerable minute conflicts settled invariably by fidelity, so happiness, if one reduces it to its important elements, is made up of struggles and anguish, and always saved by hope.

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