"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."
- John Stuart Mill,
"The Truth, the Whole Truth, and Nothing But the Truth"
Freely download "On Liberty", by John Stuart Mill, here: