History indicates that individual liberty is intermittently subjected to extraordinary perils. Even countries dedicated to government by the people are not free from such cyclical dangers. ... Test oaths are notorious tools of tyranny. When used to shackle the mind they are, or at least they should be, unspeakably odious to a free people. Test oaths are made still more dangerous when combined with bills of attainder which like this Oklahoma statute impose pains and penalties for past lawful associations and utterances.... Governments need and have ample power to punish treasonable acts. But it does not follow that they must have a further power to punish thought and speech as distinguished from acts. Our own free society should never forget that laws which stigmatize and penalize thought and speech of the unorthodox have a way of reaching, ensnaring and silencing many more people than at first intended. We must have freedom of speech for all or we will in the long run have it for none but the cringing and the craven. And I cannot too often repeat my belief that the right to speak on matters of public concern must be wholly free or eventually be wholly lost.