The other boys
who were being brought up and educated with St. Mungo by St. Serf are said
to have been jealous of the love shown to him by their master, and to have
done what they could to do him mischief. One story tells that a favourite
tame robin of St. Serf was by accident killed by one or more of his
youthful disciples, who laid the blame on
Kentigern; whereon he took the bird in his
hand, and having made over it the sign of the
cross, its life was instantly restored, and it flew chirping or carolling
to its master.
This is the famous "bird that never
flew" of the rhyme on the armorial insignia of the city of St. Mungo.