Why, you ask, are there such terrible things as volcanos?
Of what use can they be?
They are of use enough, my child; and of many more uses, doubt not, than we know as yet, or ever shall know.

But of one of their uses I can tell you.
They make, or help to make, divers and sundry curious things, from gunpowder to your body and mine.
What?
I can understand their helping to make gunpowder, because the sulphur in it is often found round volcanos; and I know the story of the brave Spaniard who, when his fellows wanted materials for gunpowder, had himself lowered in a basket down the crater of a South American volcano, and gathered sulphur for them off the burning cliffs: but how can volcanos help to make me?
Am I made of lava?
Or is there lava in me?
My child, I did not say that volcanos helped to make you.

I said that they helped to make your body; which is a very different matter, as I beg you to remember, now and always.

Your body is no more you yourself than the hoop which you trundle, or the pony which you ride.

It is, like them, your servant, your tool, your instrument, your organ, with which you work: and a very useful, trusty, cunningly-contrived organ it is; and therefore I advise you to make good use of it, for you are responsible for it.