Jesus declares, 'I am the good shepherd.' He defines that shepherd by intimate knowledge of the sheep and willingness to lay down his life for them, in contrast to a hired worker who flees when the wolf comes.
The imagery is pastoral, royal, prophetic, and deeply scriptural.
Israel's Scriptures call God the shepherd of his people and also use shepherd language for kings and leaders. Ezekiel 34 is especially important: corrupt shepherds feed themselves rather than the flock, God promises to rescue his sheep, and he promises a Davidic shepherd over them. Psalm 23 and other texts likewise portray the LORD as shepherd. A hired worker was not inherently dishonest, but lacking the owner's relationship to the flock could make self-preservation more understandable when danger arrived.
The Old Testament background gives Jesus' claim unusual weight. He does not merely present himself as a particularly compassionate rural worker.
He occupies imagery associated both with God's own care for Israel and with the promised Davidic shepherd, then defines his shepherding through voluntary self-sacrifice for the sheep.