“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 peculiar evil of silencing the expression of an opinion is, that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.”

“Those who never retract their opinions love themselves more than they love truth.”

“We all know dogmatists who are more concerned about holding their opinions than about investigating their truth. ... if they are mistaken, they will never discover it; they have condemned themselves to perpetual error. Human beings (including myself) sometimes use their beliefs for wish-fulfillment. Too often we believe what we want to be true.”

“There is no error more common than that of thinking that those who are the causes or occasions of great tragedies share in the feelings suitable to the tragic mood: no error more fatal than expecting it of them. The martyr in his 'shirt of flame' may be looking on the face of God, but to him who is piling the faggots or loosening the logs for the blast the whole scene is no more than the slaying of an ox is to the butcher, or the felling of a tree to the charcoal burner in the forest, or the fall of a flower to one who is mowing down the grass with a scythe. Great passions are for the great of soul, and great events can be seen only by those who are on a level with them.”

“Few suffer more than those who refuse to forgive themselves.”