Complex sentence: Dunne had always turned away praise of the Dooley pieces from those who knew of his authorship, wishing to be known as a serious writer; because of the dialect, the Dooley columns were more difficult for him than writing editorials and columns in plain English.
Split into simpler sentences: Dunne had always turned away praise of the Dooley pieces from those who knew of his authorship, wishing to be known as a serious writer. Because of the dialect, the Dooley columns were more difficult for him than writing editorials and columns in plain English.