孔子云：三十而立，四十而不惑，五十而知天命。
Kong Zi: cloud at forty and perplexed, fifty to know your destiny.
子曰：“吾十有五而志于学，三十而立，四十而不惑，五十而知天命，六十而耳顺，七十而从心所欲，不逾矩。”
The Master said, "At fifteen, I had my mind bent on learning. At thirty, I stood firm. At forty, I had no doubts. At fifty, I knew the decrees of Heaven."
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