[Footnote 21: "Modern Painters," Chapter IV.] When you stand some day on one of the high peaks of the Rocky Mountains, and look out over the great fields of upheaved stone, you will notice how closely the parallel ridges resemble ranks of waves making toward a shore. Like sea waves also, the vast backs of these waves of stone are long and sloping, while their fronts are comparatively short and much steeper. Another thing that makes you feel as if you were looking out upon a sea whose waves had been changed to stone is the fact that these stone waves are not only green but have white caps; for in the valleys, and far up the sides of the mountains, are the forests with the perennial green of their pines, and on the peaks the eternal snows. [Illustration: "AND EVERY TOSSING OF THEIR BOUNDLESS CRESTS"] Not only is the mounting and forward drive of waves repeated in mountain forms, but also the whirlpools among the rocks when sea waves reach the shore. Says the famous French geographer, Reclus[22]: "The centre of the Pyrenees resembles a great whirlpool around which the mountains rise like enormous waves." [Footnote 22: "The Earth."] Finally we might imagine that the mountains, like the mountain streams, hear the call of the sea and are stirred by it. For, again to quote from Ruskin's wonderful chapter on the nature of the thing we call a mountain: "Behold as we look farther into it, it is all touched and troubled. The rock trembles through its every fibre, like the chords of an Æolian harp--like the stillest air of spring with the echoes of a child's voice. Into the heart of all those great mountains and through every tossing of their boundless crests and deep beneath all their unfathomable defiles, flows that strange quivering of their substance. "'I beheld the mountains and lo they trembled; and all the hills moved lightly.'" [Illustration: _From Norton's "Elements of Geology." By permission of Ginn and Company_ "THAT STRANGE QUIVERING OF THEIR SUBSTANCE" This picture shows mountain-peaks carved in folded strata in the Rocky Mountains in Montana. How well it illustrates Ruskin's grand lines. ] HIDE AND SEEK IN THE LIBRARY Of course you saw that the Greeks meant the story of Phaeton to account, among other things, for the origin of deserts, but what is there in it that would lead one to believe the Greeks knew there were such things as volcanoes? Read what the encyclopedia says about volcanoes and Vulcan and the physical geography of Greece and the Greek islands. Where is Mount Stromboli and why is it called "The Lighthouse of the Mediterranean"? On which of our coasts do we have young and growing mountains, and on which old mountains that are much worn down?