"Respect for the elderly is the first sign of civilization."

"The most difficult thing in life is to know yourself."

"It is not the quantity of knowledge but the quality of knowledge that determines the future of humanity."

"The higher the man, the more he is dependent on other people, and the less free he is."

"Freethinkers are those who are willing to use their minds without prejudice and without fearing to understand things that clash with their own customs, privileges, or beliefs."