The Gospel of the Mass tells us that Jesus was casting out a demon that was mute, and as soon as the demon went out, the mute spoke, and the crowd was amazed.
Sickness, a physical ailment normally unrelated to sin, is a symbol of the state in which sinful man finds himself; spiritually he is blind, deaf, paralytic.... The healings that Jesus performs, besides the concrete and historical fact of healing, are also a symbol: they represent the spiritual healing that he comes to perform in men. Many of Jesus' gestures towards the sick are like an image of the sacraments.
Regarding the Gospel passage read at Mass, St. John Chrysostom comments that this man "could not present his supplication himself, for he was mute; nor could he pray to the others, for the devil had tied his tongue, and with his tongue he had tied his soul. The devil had him well bound.
When in personal prayer we do not speak to the Lord about our miseries and we do not beg him to cure them, or when we do not expose our miseries in spiritual direction, when we keep silent because pride has closed our lips, the disease becomes practically incurable. Not speaking of the damage suffered by the soul is often accompanied by not listening; the soul becomes deaf to the requests of God, arguments and reasons that could give light to return to the right path are rejected. On the other hand, it will be easy for us to open our hearts with sincerity if we try to live this advice: "... do not be frightened when you notice the burden of the poor body and the human passions: it would be foolish and naively childish for you to learn now that "it" exists. Your misery is not an obstacle, but an incentive for you to unite yourself more closely to God, to seek Him with constancy, because He purifies us".
As we repeat today, in the responsorial Psalm of the Mass, May you hear his voice today: do not harden your hearts , let us formulate the resolution not to resist grace, always being very sincere.