The real courage here isn't simply about ambition—it's about accepting that safety and discovery are fundamentally opposed. Eliot suggests that timidity doesn't protect us; it merely guarantees we'll never learn our actual limits, mistaking caution for wisdom. A musician who never plays in front of an audience because she fears imperfection will never discover whether she could have become excellent, or whether the fear itself was the only real obstacle. The quote cuts against the respectable advice to "know your limits," because limits, it turns out, are invisible until you cross them.