Put your ear to one end of a soft bolster, and let some one hit the other end.  You will hear hardly any noise, and will not feel the blow at all.  Put your ear to one end of a hard piece of wood, and let some one hit the other.  You will hear a smart tap; and perhaps feel a smart tap, too.  When you are older, and learn the laws of sound, and of motion among the particles of bodies, you will know why.  Meanwhile you may comfort yourself with the thought that Madam How has (doubtless by command of Lady Why) prepared a safe soft bed for this good people of Britain—­not that they may lie and sleep on it, but work and till, plant and build and manufacture, and thrive in peace and comfort, we will trust and pray, for many a hundred years to come.  All that the steam inside the earth is likely to do to us, is to raise parts of this island (as Hartford Bridge Flats were raised, ages ago, out of the old icy sea) so slowly, probably, that no man can tell whether they are rising or not.  Or again, the steam-power may be even now dying out under our island, and letting parts of it sink slowly into the sea, as some wise friends of mine think that the fens in Norfolk and Cambridgeshire are sinking now.  I have shown you where that kind of work has gone on in Norfolk; how the brow of Sandringham Hill was once a sea-cliff, and Dersingham Bog at its foot a shallow sea; and therefore that the land has risen there.  How, again, at Hunstanton Station there is a beach of sea-shells twenty feet above high-water mark, showing that the land has risen there likewise.  And how, farther north again, at Brancaster, there are forests of oak, and fir, and alder, with their roots still in the soil, far below high-water mark, and only uncovered at low tide; which is a plain sign that there the land has sunk.  You surely recollect the sunken forest at Brancaster, and the beautiful shells we picked up in its gullies, and the millions of live Pholases boring into the clay and peat which once was firm dry land, fed over by giant oxen, and giant stags likewise, and perhaps by the mammoth himself, the great woolly elephant whose teeth the fishermen dredge up in the sea outside?  You recollect that?  Then remember that as that Norfolk shore has changed, so slowly but surely is the whole world changing around us.  Hartford Bridge Flat here, for instance, how has it changed!  Ages ago it was the gravelly bottom of a sea.  Then the steam-power underground raised it up slowly, through long ages, till it became dry land.  And ages hence, perhaps, it will have become a sea-bottom once more.  Washed slowly by the rain, or sunk by the dying out of the steam-power underground, it will go down again to the place from whence it came.  Seas will roll where we stand now, and new lands will rise where seas now roll.  For all things on this earth, from the tiniest flower to the tallest mountain, change and change all day long.  Every atom of matter moves perpetually; and nothing “continues in one stay.”  The solid-seeming earth on which you stand is but a heaving bubble, bursting ever and anon in this place and in that.  Only above all, and through all, and with all, is One who does not move nor change, but is the same yesterday, to-day, and for ever.  And on Him, my child, and not on this bubble of an earth, do you and I, and all mankind, depend.