One thorn of experience is worth a whole wilderness of warning. (James Russell Lowell, British Poet and critic)

One thorn of experience is worth a whole wilderness of warning. (James Russell Lowell, British Poet and critic) 

一次痛苦的经验抵得上千百次的告诫。(英国诗人、批评家 洛威尔 .J. R .)