Do I mean their shape?
No, my child; no. I mean something which makes the shape of things, and the matter of them likewise, but which folks have lost sight of nowadays, and do not seem likely to get sight of again for a few hundred years. So I suppose that you need not trouble your head about it, but may just follow the fashions as long as they last.
About this piece of lime, however, Analysis can tell us a great deal. And we may trust what he says, and believe that he understands what he says.
Why?
Think now. If you took your watch to pieces, you would probably spoil it for ever; you would have perhaps broken, and certainly mislaid, some of the bits; and not even a watchmaker could put it together again. You would have analysed the watch wrongly. But if a watchmaker took it to pieces then any other watchmaker could put it together again to go as well as ever, because they both understand the works, how they fit into each other, and what the use and the power of each is. Its being put together again rightly would be a proof that it had been taken to pieces rightly.
And so with Master Analysis. If he can take a thing to pieces so that his brother Synthesis can put it together again, you may be sure that he has done his work rightly.
Now he can take a bit of chalk to pieces, so that it shall become several different things, none of which is chalk, or like chalk at all. And then his brother Synthesis can put them together again, so that they shall become chalk, as they were before. He can do that very nearly, but not quite. There is, in every average piece of chalk, something which he cannot make into chalk again when he has once unmade it.
What that is I will show you presently; and a wonderful tale hangs thereby. But first we will let Analysis tell us what chalk is made of, as far as he knows.
He will say—Chalk is carbonate of lime.
But what is carbonate of lime made of?