The opinion prevailed among advanced minds that it was time that belief should be replaced increasingly by knowledge; belief that did not itself rest on knowledge was superstition, and as such had to be opposed.
Altered opinions do not alter a man's character (or do so very little); but they do illuminate individual aspects of the constellation of his personality which with a different constellation of opinions had hitherto remained dark and unrecognizable.
No two men see the world exactly alike, and different temperaments will apply in different ways a principle that they both acknowledge. The same man will, indeed, often see and judge the same things differently on different occasions: early convictions must give way to more mature ones. Nevertheless, may not the opinions that a man holds and expresses withstand all trials, if he only remains true to himself and others?
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.