Verse 18. - Wheresoever it taketh him (καταλάβη); literally, it seizeth hold of him. This is the Greek word from which comes our "catalepsy," the active form of "epilepsy." It teareth him (ῤήσσει). This is doubtless the literal meaning. But there is much evidence to show that it means here "it striketh or throweth him down." This is the reudering of the Peshito Syriac, and of the Vulgate. The same interpretation is also given by Hesychius as one of the meanings of the word. St. Luke (Luke 9:39) describes the symptoms thus: "A spirit taketh him, and he suddenly crieth out, and it teareth him (σπαράσσει αὐτὸν) that he foameth (μετὰ ἀφροῦ), and it hardly departeth from him, bruising him sorely." This it will be remembered is the record of one who was himself a physician. He grindeth his teeth, and pineth away (ξηραίνεται), as though the springs of his life were dried up. The father of the boy is here minutely describing the symptoms when the fit was upon him. He seems here to express the stiffness and rigidity of the body in the approaches of the malady. And I spake to thy disciples that they should cast it out; and they were not able. They had tried and failed. This failure is attributed by our Lord (see Matthew 17:20) to their want of faith; or rather to their "little faith (διὰ τὴν ὀλιγοπιστίαν ὑμῶν)."

9:14-29 The father of the suffering youth reflected on the want of power in the disciples; but Christ will have him reckon the disappointment to the want of faith. Very much is promised to our believing. If thou canst believe, it is possible that thy hard heart may be softened, thy spiritual diseases may be cured; and, weak as thou art, thou mayest be able to hold out to the end. Those that complain of unbelief, must look up to Christ for grace to help them against it, and his grace will be sufficient for them. Whom Christ cures, he cures effectually. But Satan is unwilling to be driven from those that have been long his slaves, and, when he cannot deceive or destroy the sinner, he will cause him all the terror that he can. The disciples must not think to do their work always with the same ease; some services call for more than ordinary pains.And wheresoever he taketh him,.... The spirit, or devil, whether it be near fire, or water, whatsoever danger, or dangerous place:

he teareth him; or throws him into it, or dashes him against it; or inwardly racks, tortures, and convulses him:

and he foameth; at the mouth, like one that is mad:

and gnasheth with his teeth; through the excessive pain he is in:

and pineth away; his flesh is withered, dried up, and consumed away. This was the sad deplorable case this child was in, who was his father's only child, and therefore his health and life were very desirable: now he further observes to Christ, saying,

and I spake to thy disciples that they should cast him out, and they could not. Christ being absent, he entreated the disciples, who had power against unclean spirits, to cast them out; that they would make use of it, and dispossess this dumb and evil spirit; and who did make trial to cast him out, but were not able to effect it; See Gill on Matthew 17:16.