We owe almost all our knowledge not to those who have agreed, but to those who have differed.

Assent-and you are sane- Demure-you're straightway dangerous- And handled with a Chain-.

Dissent and dissenters have no monopoly on freedom. They must tolerate opposition. They must accept dissent from their dissent.

If a community decides that some conduct is prejudicial to itself, and so decides by numbers sufficient to impose its will upon dissenters, I know of no principle which can stay its hand.

They that approve a private opinion, call it opinion; but they that mislike it, heresy, and yet heresy signifies no more than private opinion.

Freedom to differ is not limited to things that do not matter much. That would be a mere shadow of freedom. The test of its substance is the right to differ as to things that touch the heart of the existing order.

It is more often from pride than from defective understanding that people oppose established opinions: they find the best places taken in the good party and are reluctant to accept inferior ones.

In religion, it is not the sycophants or those who cling most faithfully to the status quo who are ultimately praised. It is the insurgents.

In a dead religion there are no more heresies.

Say, Not so, and you will outcircle the philosophers.