The disciples' problem...has been a loss of the sense of dependence on Jesus unique exousia which had undergirded their earlier exorcistic success. They have become blasé and thought of themselves as now the natural experts in such a case and they must learn that in spiritual conflict there is no such automatic power. Their public humiliation has been a necessary part of their re-education to the principles of the kingdom of God.
R T France, commenting on Mark 9:29 in The Gospel of Mark (NIGTC), p.370
