Lao Tzu

Knowing others is intelligence; knowing yourself is true wisdom. Mastering others is strength; mastering yourself is true power.

Lǎozi was a Chinese philosopher (also called Lao Zi, Lao Tzu, Lao Tse, or Lao Tze), The Tao Te Ching (6th–5th century BC), Ch. 33, as interpreted by Stephen Mitchell (1992).