When a new baby comes into the house Tom is rather upset. He feels that he is getting no attention and the baby takes up everyone's time. He is rather sorry for himself.
But when his parents notice he is upset they reassure him that once upon a time he too was a little baby, and needed lots of attention, and one day the baby will be a boy like him.
An important lesson, gently told, for any child facing the problem of not being an only child anymore.