He had more than a presentiment that his fatherly friend would feel some dissatisfaction, if not pain, at this turn of his destiny. In reading unwelcome news, instead of hearing it, there is the advantage that one avoids a hasty expression of impatience which may afterward be repented of. 
He feared that his fatherly friend would feel some dissatisfaction, if not pain, at this turn of his destiny, and thought a letter would avoid any hasty response which might afterward be repented of. 