This chapter illustrates the Lord's calling and commissioning in Christian service. There is a marked difference in this from the old order in the legal system of Judaism. In the old dispensation the servants were the Levites. They were born into their family and appointed their service, whether they had an exercise about it or not. But in Christianity, God's servants would no longer come from a certain family lineage, but by the Lord's call. The Lord calls and sends whom He would; He fits them for that work by their experiences in the school of God. This is illustrated by the Lord’s commissioning Peter (who had previously failed) to a work of shepherding the Lord's sheep (vss. 15-19). John, too, had a work to do (vss. 20-25).