Mark 9:29

τοῦτο τὸ γένος, etc.: This is one of the texts which very soon became misunderstood, the ascetic addition, καὶ νηστείᾳ, being at once a proof and a cause of misunderstanding. The traditional idea has been that Jesus here prescribes a certain discipline by which the exorcist could gain power to cope successfully with the most obstinate cases of possession, a course of prayer and fasting. This idea continues to dominate the mind even when the ascetic addition to the text has come to be regarded as doubtful; witness this remark: “The authorisation, however (for omitting καὶ νησ.), is not sufficient. But even if it were overwhelming, fasting would, in its essence, be implied” (Morison on Mark). What Jesus said doubtless was: “This kind can go out in (on the ground of) nothing except prayer,” and His meaning that there was no hope of success except through a believing (of course faith is implied) appeal to the almighty power of God. It was a thought of the same kind as that in Matthew 19:26 (Mark 10:27): the impossible for man is possible for God. Of course in the view of Christ, prayer, faith (vide Matthew 17:20), both in healer and in healed, was needful in all cases, but He recognised that there were certain aggravated types of disease (the present, one of them) in which the sense of dependence and trust was very specially required. In the case of the epileptic boy this had been lacking both in the father and in the disciples. Neither he nor they were hopeful of cure.