"The unexamined life is not worth living."

"Those who offer [wisdom] to all comers for money are known as sophists, prostitutors of wisdom."

"Why should we pay so much attention to what 'most people' think?"

"He would say that the rest of the world lived to eat, while he himself ate to live."

"Employ your time in improving yourself by other men's writings so that you shall come easily by what others have labored hard for."