 We are thus faced with the question whether the Smith Act prohibits advocacy and teaching of forcible overthrow as an abstract principle , divorced from any effort to instigate action to that end , so long as such advocacy or teaching is engaged in with evil intent . We hold that it does not .... In failing to distinguish between advocacy of forcible overthrow as an abstract doctrine and advocacy of action to that end , the District Court appears to have been led astray by the holding in Dennis that advocacy of violent action to be taken at some future time was enough . 
