"The human mind, when it is in a healthy state, is never satisfied with having attained a certain measure of truth; it is always aspiring to a higher."

"He who lets the world, or his own portion of it, choose his plan of life for him, has no need of any other faculty than the ape-like one of imitation."

"Truth gains more even by the errors of one who, with due study and preparation, thinks for himself, than by the true opinions of those who only hold them because they do not suffer themselves to think…"

"The greatest good for the greatest number is the measure of right and wrong."

"If all mankind minus one were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be …"