"Go on!" he demanded. "Go on! Now what?"

"Well, when you have all that said to you, it means that if you
find a doctor skulking about within ten feet of you, it is then
your perfect right to press him into your service. If you command
him to give you a ride on his back, he will have to do it. It's
undignified and he doesn't believe in it, but that's where you
have him at your mercy. He _has_ to obey; he has to go any place
you tell him to go. If you say he must take you to a toy shop,
that settles it. He has no choice in the matter. He _has_ to do
it. That is always the rule when a little boy is four years old."

David also learned that there is another peculiar thing about it.
In circumstances like this a little boy has the right, when he
arrives at the toy shop, to choose for himself the thing he wants
to buy. No grown-up will interfere with his judgment; the law
won't allow it. The trouble is that it is pretty hard for him to
make up his mind. When there is such a great array of drums and
swords and soldiers' caps and guns and bears that jump, it is not
an easy thing to select the toy that will please him most of
all.

Why not buy a train of cars and a track to run it on? But if he
bought that, then how could he get along without a jumping-jack
that threw up its arms and legs when you pulled the string? And
if he took the jumping-jack, then what about an iron savings bank
with a monkey on top that shook his head with thanks when you
dropped the money in? Lovely things, all of them, but David put
them from him. He did it with decision, but with a nervous haste
which told of wavering courage.