Who Said That? History Edition

"To be true to one's own freedom is, in essence, to honor and respect the freedom of all others."

"To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge."

"Leadership is the art of getting someone to do something you want done because he wants to do it

"Mathematics is written for mathematicians."

"For it is the duty of an astronomer to compose the history of the celestial motions through careful and expert study."