“He who can, does. He who cannot, teaches. ”

“Those who can do, those who can't teach.”

“He who has never hoped can never despair”

“Those who talk most about the blessings of marriage and the constancy of its vows are the very people who declare that if the chain were broken and the prisoners left free to choose, the whole social fabric would fly asunder. You cannot have the argument both ways. If the prisoner is happy, why lock him in? If he is not, why pretend that he is?”

“Those who cannot change their minds cannot change anything.”

“If you teach a man anything, he will never learn.”

“Progress is impossible without change; and those who cannot change their minds cannot change anything.”