Today's first reading from Isaiah and the Gospel from Mark are excellent examples of the effectiveness of God's word to realize what it announces.
For his part, the prophet served as God's mouthpiece, encouraging the people to be stronger than their fears because God -- who sees all, knows all and cares for all -- is coming to save! That promised salvation will be marked by an end of physical debilities so that all may hear, see and understand the salvific gifts of God and break out into joyful, grateful praise.
What Isaiah promised, Mark pronounced as fulfilled in Jesus' action of healing the deaf one who had a speech impediment. Jesus would also give sight to the blind and cure the lame, all in an effort to illustrate the potency of God's word and power at work in him, inviting to faith and conversion all those who witnessed his actions.