Of course, the same things are in what you eat now; only now they come
in a form more difficult to deal with, and the labor of detaching them
from the surrounding ingredients is much greater. The whole business
indeed of this famous machine which we are studying consists in
unfastening the links which hold things together, and in laying aside
what is useful, to be sent to the blood divested of the refuse. The
stomach was too feeble in your infancy to have encountered the work
it has to do now. It is for this reason that God devised for the benefit
of little children that excellent nourishment--milk--which contains,
all ready for use, every ingredient the blood wants; and is almost,
in fact, blood ready made.

Only think, my child, what you owe to her who gave you this nourishment!
It was actually her blood she was giving you; her blood which entered
into your veins, and which wrought within you in the wonderful way
which I have been describing. Other people gave you sugar-plums, kisses,
and toys; but she gave you the teeth which crunched the sugar-plums,
the flesh of the rosy cheeks which got the kisses, and of the little
hands which handled the toys. If ever you can forget this, you are
ungrateful indeed!

Now, beware of going on to ask me how we know that there are so many
sorts of things in milk, or I shall end by getting angry. Question
after question; why, you might drive me in this way to the end of the
world, and we should never reach the point we are aiming at. We have
already traveled far away from the teeth, concerning which I wanted
to talk to you at this time, but our lesson is nearly over and we have
scarcely said a word about them! One cannot learn everything at once.
Upon the point in question you must take my word; and as you may
believe, I would not run the risk of being contradicted before you,