Matthew 17:15

“Lord, have mercy on my son, etc.] He addressed him with great marks of honour and respect, not only by gesture, but by words; he craves mercy, pity, and compassion; for the case he had to present, was a miserable one; and his earnestness and importunity he hoped might be excused, since it was for a child of his own. Luke adds “for he is mine only child”; and therefore his affection for him must be thought to be very strong, and he greatly concerned for its grievous affliction, and earnestly desirous of its health and life. For he is lunatic: not a mad man, but troubled with the epileptic disease; upon which, as on madness or lunacy, the changes and full of the moon have an influence: hence…”

“Lord, have mercy - The word “Lord” here means “Sir,” a title of civility, not implying divinity. My son - This was an only son (Luke). He was possessed with a devil. This calamity was attended with the following symptoms: he was lunatic (see the notes at Matthew 4:24); he was sore vexed; that is, he suffered greatly, or was greatly afflicted; he fell often suddenly, in the manner of persons having epileptic fits; he was dumb - that is, he was mute except when the seizure was coming upon him, for Luke says that when the spirit took him he cried suddenly out; he foamed and gnashed with his teeth, and wasted away, or became poor and emaciated. Luke Luke 9:39 adds of the evil spirit, “it teareth…”

“He is lunatic - This word might with great propriety he used, though the case was mostly preternatural; as the evil spirit would undoubtedly take advantage of the influence which the changes of the moon have on the brain and nerves. Matthew 17:17”

“have: Mat 15:22; Mar 5:22, Mar 5:23, Mar 9:22; Luk 9:38-42; Joh 4:46, Joh 4:47 for: Mat 4:24; Mar 9:17, Mar 9:18, Mar 9:20-22 he is: Σεληνιαζεται \[Strong's G4583\], from σεληνη \[Strong's G4582\], the moon, one who was affected with his disorder at the change and full of the moon. This is the case in some kinds of madness and epilepsy. This youth was no doubt epileptic; but it was evidently either produced or taken advantage of by a demon or evil spirit. for ofttimes: Mat 8:31, Mat 8:32; Job 1:10-19, Job 2:7; Mar 5:4, Mar 5:5 Matthew 17:16”