To know, is to know that you know nothing. That is the meaning of true knowledge. When you say something, say what you know. When you don't know something, say you don't know. That is knowledge.

Never tire to study. And to teach to others

Writing cannot express all words, words cannot encompass all ideas.

He who knows all the answers has not been asked all the questions.

Excessive (population) growth may reduce output per worker, repress levels of living for the masses and engender strife

Be loyal to yourself, charitable to neighbours, nothing more.

Things have their roots and branches. Affairs have their beginnings and their ends. To know what is first and what is last will lead one near the Way.