MATTHEW 17 14 And when they had come to the multitude, a man came to Him, kneeling down to Him and saying, 15 “Lord, have mercy on my son, for he is an epileptic and suffers severely; for he often falls into the fire and often into the water. 16 So I brought him to Your disciples, but they could not cure him.” 17 Then Jesus answered and said, “O faithless and perverse generation, how long shall I be with you? How long shall I bear with you? Bring him here to Me.” 18 And Jesus rebuked the demon, and it came out of him; and the child was cured from that very hour.19 Then the disciples came to Jesus privately and said, “Why could we not cast it out?”20 So Jesus said to them, “Because of your unbelief; for assuredly, I say to you, if you have faith as a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you. 21 However, this kind does not go out except by prayer and fasting.”

If every disease and weakness which our Savior cured at that time among the people represents different symptoms in the soul, it stands to reason that by the paralytics are symbolized the palsied in soul, who keep it lying paralyzed in the body. By those who are blind are symbolized those who are blind in respect of things seen by the soul alone, and these are really blind. And by the deaf are symbolized those who are deaf in regard to the reception of the word of salvation. On the same principle it will be necessary that the matters regarding the epileptic should be investigated. This disease attacks those who suffer from it at considerable intervals, during which time he who suffers from it seems in no way to differ from the man in good health, at the season when the epilepsy is not working on him. You will find some souls that are often considered to be healthy suffering from symptoms like these in their chastity and the other virtues. But there comes a time when they are attacked by a kind of epilepsy, and then they seem to fall from their solid foundation and are seized by the deceits and other desires of this world.
(Origen)