And he asked his father,.... As he lay rolling about in this miserable condition, that the length and stubbornness of his disorder might be known, and so the cure the more remarkable, and appear the more expressive of his divine power and goodness:

how long is it ago since this came unto him? since this evil spirit entered into him, and these disorders have attended him?

and he said of a child; or "from his infancy"; so that it was not for any actual sin that he had committed, that this sore affiction came upon him; and yet he could not be without sin, since it was not agreeable to the justice, mercy, and goodness of God, to afflict, or suffer to be afflicted, one that is innocent; and therefore must be tainted with original sin, which is the source and spring of all afflictions, calamities and judgments.

And he asked his father, How long is it ago since this came unto him? And he said, Of a child.

21. And he asked his father, How long is it ago since this came unto him? And he said, Of a child, &c.-Having told briefly the affecting features of the case, the poor father, half dispirited by the failure of the disciples and the aggravated virulence of the malady itself in presence of their Master, yet encouraged too by what he had heard of Christ, by the severe rebuke He had given to His disciples for not having faith enough to cure the boy, and by the dignity with which He had ordered him to be brought to Him-in this mixed state of mind, he closes his description of the case with these touching words:

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.