"Be slow to fall into friendship, but when you are in, continue firm and constant."
"Be slow to fall into Friendship; but when thou art in, continue firm & constant."
"The unexamined life is not worth living."
"Beware the barrenness of a busy life."
"The secret of change is to focus all of your energy, not on fighting the old, but on building the new."
"Let him who would move the world first move himself."
"I cannot teach anybody anything, I can only make them think."
"One thing only I know, and that is that I know nothing."
"There is only one good, knowledge, and one evil, ignorance."
"The beginning of wisdom is a definition of terms."
"Beauty is a short-lived tyranny."