Discipline strengthens the mind so that it becomes impervious to the corroding influence of fear.
Fear comes from uncertainty. When we are absolutely certain whether of our worth or worthlessness we are almost impervious to fear.
It is of course further indication that a fundamentalist right has really taken over much of the Republican Party People might cite George Bush as proof that you can be totally impervious to the effects of Harvard and Yale education.
So the poet who wants to be something that he cannot be and is a failure in plain life makes up fictitious versions of his predicament that are interesting even to other persons because nobody is a perfect automobile salesman.