Book 2 of the Analects is named after its opening words,
子曰：
为政以德 'The Master said: govern by virtue'. It holds some of the best-known sayings: Confucius's life in stages from fifteen to seventy, the source of
三十而立, and
学而不思则罔，
思而不学则殆 'learning without thought is lost; thought without learning is dangerous'.
