There is only one passion, the passion for happiness.
(Denis Diderot (1713-1784), French philosopher. repr. In Selected Writings, ed. Lester G. Crocker (1966). Elements of Physiology, "Will, Freedom," (notes written 1774-1780, originally published 1875-1877).)
(Friedrich Nietzsche (1844-1900), German philosopher, classical scholar, critic of culture. Friedrich Nietzsche, Sämtliche Werke: Kritische Studienausgabe, vol. 5, p. 92, eds. Giorgio Colli and Mazzino Montinari, Berlin, de Gruyter (1980). Beyond Good and Evil, "Fourth Part: Maxims and Interludes," section 106 (1886).)