"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."

"Hold faithfulness and sincerity as first principles. Then no friends will be unlike yourself."

"Reviewing the old as a means of understanding the new — such a person can be a teacher."

"Is it not a pleasure, having learned something, to try it out at due intervals?"

"Everything has beauty, but not everyone sees it."