Book 9: 《子罕》 Zi Han (The Master Shunned)
《子罕》 Passage 9.23
子曰：「後生可畏，焉知來者之不如今也？四十、五十而無聞焉，斯亦不足畏也已。」
Legge Translation (1861)
The Master said: "A youth is to be regarded with respect. How do we know that his future will not be equal to our present? If he reach the age of forty or fifty, and has not made himself heard of, then indeed he will not be worth being regarded with respect."