The following comes from Scott Hahn's site:
Simon Peter, the fisherman, is the first to be called personally by Jesus in Luke’s Gospel.
His calling resembles Isaiah’s commissioning in the First Reading: Confronted with the holiness of the Lord, both Peter and Isaiah are overwhelmed by a sense of their sinfulness and inadequacy. Yet each experiences the Lord’s forgiveness and is sent to preach the good news of His mercy to the world.
No one is “fit to be called an apostle,” Paul recognizes in today’s Epistle. But by “the grace of God,” even a persecutor of the Church—as Paul once was—can be lifted up for the Lord’s service.
In the Old Testament, humanity was unfit for the divine—no man could stand in God’s presence and live (see Exodus 33:20). But in Jesus, we’re made able to speak with Him face-to-face, taste His Word on our tongue.
Today’s scene from Isaiah is recalled in every Mass. Before reading the Gospel, the priest silently asks God to cleanse his lips that he might worthily proclaim His Word.
God’s Word comes to us as it came to Peter, Paul, Isaiah, and today’s Psalmist— as a personal call to leave everything and follow Him, to surrender our weaknesses in order to be filled with His strength.
Simon put out into deep waters even though, as a professional fisherman, he knew it would be foolhardy to expect to catch anything. In humbling himself before the Lord’s command, he was exalted—his nets filled to overflowing; later, as Paul tells us, he will become the first to see the risen Lord.
Jesus has made us worthy to receive Him in the company of angels in God’s holy Temple. On our knees like Peter, with the humility of David in today’s Psalm, we thank Him with all our hearts and join in the unending hymn that Isaiah heard around God’s altar: “Holy, holy, holy….” (see also Revelation 4:8).