That seeing they may see, and not perceive; and hearing they may hear, and not understand; lest at any time they should be converted, and their sins should be forgiven them.
All Commentaries on Mark 4:12 Go To Mark 4
Cyril of Alexandria
AD 444
Parables are word pictures not of visible things, but rather of things of the mind and the spirit. That which cannot be seen with the eyes of the body, a parable will reveal to the eyes of the mind, informing the subtlety of the intellect by means of things perceivable by the senses, and as it were tangible. .