Now, are you curious to know what this treasure is?  Have you seen already that it is only coal, and do you wonder that I think it is so precious?  Look a little closer, while our guide lets the light of his lamp fall upon the black wall at your side.  Do you see the delicate tracery of ferns, more beautiful than the fairest drawing.  See, beneath your feet is the marking of great tree-trunks lying aslant across the floor, and the forms of gigantic palm-leaves strewed among them.  Here is something different, rounded like a nut-shell; you can split off one side, and behold there is the nut lying snugly as does any chestnut in its bur!

Did you notice the great pillars of coal that are left to uphold the roof?  Let us look at them; for perhaps we can examine them more closely than we can the roof, and the sides of these halls.  Here are mosses and little leaves, and sometimes an odd-looking little body that is not unlike some of the sea-creatures we found at the beach last summer; and every thing is made of coal, nothing but coal.  How did it happen, and what does it mean?  Ferns and palms, mosses and trees and animals, all perfect, all beautiful, and yet all hidden away under this hill, and turned into shining black coal.

Now, I can very well remember when I first saw a coal fire, and how odd it looked to see what seemed to be burning stones.  For, when I was a little girl, we always had logs of wood blazing in an open fireplace, and so did many other people, and coal was just coming into use for fuel.  What should we have done, if everybody had kept on burning wood to this day?  There would have been scarcely a tree left standing; for think of all the locomotives and engines in factories, besides all the fires in houses and churches and schoolhouses.  But God knew that we should have need of other fuel besides wood, and so he made great forests to grow on the earth before he had made any men to live upon it.  These forests were of trees, different in some ways from those we have now, great ferns as tall as this house, and mosses as high as little trees, and palm-leaves of enormous size.  And, when they were all prepared, he planned how they should best be stored up for the use of his children, who would not be here to use them for many thousand years to come.  So he let them grow and ripen and fall to the ground, and then the great rocks were piled above them to crowd them compactly together, and they were heated and heavily pressed, until, as the ages went by, they changed slowly into these hard, black, shining stones, and became better fuel than any wood, because the substance of wood was concentrated in them.  Then the hills were piled up on top of it all; but here and there some edge of a coal-bed was tilted up, and appeared above the ground.  This served for a hint to curious men, to make them ask “What is this?” and “What is it good for?” and so at last, following their questions, to find their way to the secret stores, and make an open doorway,