and when they had fulfilled the days, as they were returning, the boy Jesus stayed behind in Jerusalem. Joseph and his mother didn't know it,

 We have already seen that when a boy was born, the local musicians congregated at the house to greet him with simple music. Jesus was born in a stable in Bethlehem and therefore that ceremony could not be carried out. It is a lovely thought that the minstrelsy of heaven took the place of the minstrelsy of earth, and angels sang the songs for Jesus that the earthly singers could not sing. 