From Zhuge Liang's (
诸葛亮, Three Kingdoms)
《诫子书》 ('Letter Admonishing My Son'), written to his son
诸葛瞻:
非淡泊无以明志,非宁静无以致远 - 'without detachment, one cannot clarify one's ambition; without serenity, one cannot reach what is far.' One of the most famous father-to-son admonitions in Chinese literature.