Bai Juyi (772-846 CE) was an important poet and government official during the Tang Dynasty in China. On one occasion, he sought essential instructions in the Dharma from a monk.
The monk quoted summary of the doctrine that the Buddha Shakyamuni offered:
"Avoid evil. Do good. Purify your mind”.
Bai Juyi was not impressed. "Even three year old knows these words. What I want to know is the most profound and fundamental statement of the Buddha".
The monk replied," Yes! A three year old knows these words, but even the elders of eighty still have not put them into practice."