Rejoice with me (συνχαρητε μο). Second aorist passive of συνχαιρω, an old and common verb for mutual joy as in Philippians 2:17. Joy demands fellowship. Same form in verse Luke 15:9. So the shepherd

calls together (συνκαλε, note συν again) both his friends and his neighbours. This picture of the Good Shepherd has captured the eye of many artists through the ages.