“They who study mathematiks only to fix their minds, and render them the steadyer to apply to all other things, as there are many who profess to do, are as wise as those who think by rowing boats, to learn to swim.”

Tripadis

Source Book in Ancient Philosophy (1907), The Golden Sayings of Democritus

Source: The enjoyments of life (such was now my theory) are sufficient to make it a pleasant thing, when they are taken en passant, without being made a principal object. Once make them so, and they are immediately felt to be insufficient. They will not bear a scrutinizing examination. Ask yourself whether you are happy, and you cease to be so. The only chance is to treat, not happiness, but some end external to it, as the purpose of life. Let your self-consciousness, your scrutiny, your self-interrogation, exhaust themselves on that; and if otherwise fortunately circumstanced you will inhale happiness with the air you breathe, without dwelling on it or thinking about it, without either forestalling it in imagination, or putting it to flight by fatal questioning. This theory now became the basis of my philosophy of life. And I still hold to it as the best theory for all those who have but a moderate degree of sensibility and of capacity for enjoyment; that is, for the great majority of mankind."

Autobiography, Ch 5, https://www.gutenberg.org/files/10378/10378-h/10378-h.htm#link2H_NOTE https://www.laits.utexas.edu/poltheory/mill/auto/auto.c05.html source: Autobiography (1873), Ch. 5: A Crisis in My Mental History (p. 100)

Quoted by Bishop Jean-Pierre Camus in The Spirit of Saint Francis de Sales, ch. 1, Pg. 3 (1880)

Source: On Liberty (1859), Ch. II: Of the Liberty of Thought and Discussion

Whether 't was rightfully said, Live Concealed
Bartlett's Familiar Quotations, 10th ed. (1919)

Source: Celebrating Silence: Excerpts from Five Years of Weekly Knowledge 1995-2000