Well -- thanks once more to Peter and Iona Opie and The Oxford Book of Children's Verse -- we can read the rest of the story as penned by Sarah Josepha Hale (1788-1879).
And so the teacher turned him out,
But still he lingered near,
And waited patiently about,
Till Mary did appear.
And then he ran to her and laid
His head upon her arm,
As if he said, "I'm not afraid --
You'll shield me from all harm."
"What makes the lamb love Mary so?"
The little children cry;
"Oh, Mary loves the lamb, you know,"
The teacher did reply,
"And you each gentle animal
In confidence may bind,
And make it follow at your call,
If you are always kind."