In each case they [the courts] must ask whether the gravity of the 'evil', discounted by its improbability, justifies such invasion of free speech as is necessary to avoid the danger.... The American Communist Party, of which the defendants are the controlling spirits, is a highly articulated, well contrived, far spread organization, numbering thousands of adherents, rigidly and ruthlessly disciplined, many of whom are infused with a passionate Utopian faith that is to redeem mankind.... The violent capture of all existing governments is one article of the creed of that faith [communism], which abjures the possibility of success by lawful means.[120]