 " 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 . " 
