Saturday, 18th Week in Ordinary Time
From: Matthew 17:14-20
The Curing of an Epileptic Boy
 And when they came to the crowd, a man came up to him and kneeling before him said,  "Lord, have mercy on my son, for he is an epileptic and he suffers terribly; for often he falls into the fire, and often into the water.  And I brought him to your disciples, and they could not heal him."  And Jesus answered, "O faithless and perverse generation, how long am I to be with you? How long am I to bear with you? Bring him here to me."  And Jesus rebuked him, and the demon came out of him, and the boy was cured instantly.  Then the disciples came to Jesus privately and said, "Why could we not cast it out?"  He said to them, "Because of your little faith. For truly, I say to you, if you have faith as a grain of mustard seed, you will say to this mountain, 'Move hence to yonder place,' and it will move; and nothing will be impossible to you."
14-21. This episode of the curing of the boy shows both Christ's omnipotence and the power of prayer full of faith. Because of his deep union with Christ, a Christian shares, through faith, in God's own omnipotence, to such an extent that Jesus actually says on another occasion, "he who believes in me will also do the works that I do; and greater works than these will he do, because I go to the Father" (Jn 14:12).
Our Lord tells the Apostles that if they had faith they would be able to work miracles, to move mountains. "Moving mountains" was probably a proverbial saying. God would certainly let a believer move a mountain if that were necessary for his glory and for the edification of one's neighbor; however, Christ's promise is fulfilled everyday in a much more exalted way. Some Fathers of the Church (St. Jerome, St. Augustine) say that "a mountain is moved" every time someone is divinely aided to do something which exceed man's natural powers. This clearly happens in the work of our sanctification, which the Paraclete effects in our souls when we are docile to him and receive with faith and love the grace given us in the sacraments: we benefit from the sacraments to a greater or lesser degree depending on the dispositions with which we receive them. Sanctification is something more sublime than moving mountains, and it is something which is happening every day in so many holy souls, even though most people do not notice it.
The Apostles and many saints down the centuries have in fact worked amazing material miracles; but the greatest and most important miracles were, are and will be the miracles of souls dead through sin and ignorance being reborn and developing in the new life of the children of God.
20. Here and in the parable of Matthew 13:31-32 the main force of the comparison lies in the fact that a very small seed--the mustard seed--produces a large shrub up to three meters (ten feet) high: even a very small act of genuine faith can produce surprising results.
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.