Confucius, 《論語 - The Analects》, Book II《為政 - Wei Zheng》

James Legge, The Chinese Classics. Volume I. Confucian analects, the Great Learning, and the Doctrine of the Mean, revised second edition, Clarendon Press, 1893. pp. 149-1511
# 11

The Master said, “If a man keeps cherishing his old knowledge, so as continually to be acquiring new, he may be a teacher of others.”


# 17

The Master said, “You, shall I teach you what knowledge is? When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it - this is knowledge.”