F. L. Lucas on the sources of happiness

Vitality of mind and body; the activity to employ and maintain them; the zest and curiosity that they can animate; freedom to travel widely in nature and art, in countries of the world and countries of the mind; human affections; and the gift of gaiety—these seem to me, then, the main causes of happiness. I am surprised to find how few and simple they are.

—F.L. Lucas, The Greatest Problem

(And for extra credit, please see Lin Yutang on the philosophy of half-and-half, which remains closest, after all these years, to my own personal idea of happiness.)