It is a good letter about writing and the life of a writer in general, and I agree with what Steinbeck is saying here. Time and again we see questions on writing forums asking "Can I do X?" The answer is always "yes," followed by the caveat "if you do it effectively." I think it holds true for all writers, regardless of genre. My signature line is taken from this letter.
John Steinbeck - Advice to an Author
John Steinbeck - Advice to an Author
Mystagogue
Dark Lord