It is only the very wisest and the very stupidest who never change.
Writing cannot express all words, words cannot encompass all ideas.
To study and at times practice what one has learned, is this not a pleasure?
Make faithfulness and truth thy masters: have no friends unlike thyself: be not ashamed to mend thy faults.
Don't use cannon to kill musquito.
If language is not rectified, words do not correspond to meaning, and if words do not correspond to meaning, our deeds cannot be accomplished.