Who shall therefore say that a PEBBLE from the sea-shore has nothing remarkable in it or about it, merely because the passing schoolboy can pick it up if he pleases, and, without looking at it for a moment, can fling it at the head of a gull, or dash it to atoms against a larger stone? It is a microcosm in itself; and if it lead us on to further inquiry and patient thought, it will amply repay our trouble, though we _have_ loitered away a summer morn or an autumn evening among the Pebbles of the Beach. CHAPTER X. GUESSES AT THE PROBABLE FEATURES OF A PAST SCENE.—WHAT WAS THE EARTH’S _COMMENCING_ ROTATION.—LAW OF THE TIDES AT SUCH A TIME, AND CORRESPONDING ACTION OF THE SEA UPON THE LAND.—ORIGINAL CHARACTER OF THESE FOSSIL FORMS. Whatever may be thought of the apparent scope or tendency of some of the geological theories which are rife in the present day, no person who has really considered the subject in its principal bearings has any doubt that the surface of our globe, both as to the land and the water, was once very different from what it is now. All sound argument must allow this to be possible: all careful investigation pronounces it to be the fact. There are potent “menstrua” and mighty furnaces in the laboratory of Nature; and while the actual _amount_ of MATTER in existence has, we suppose, never varied since the original creative act which gave birth to “the heaven and the earth,” the conditions, sensible or chemical, under which that matter presents itself have altered from century to century and from moment to moment. It is impossible to deem otherwise, if we believe that the “laws” which are established now in this creation were established then. Let us take, for instance, the law of Universal Gravitation, that law by which the heavenly bodies move in their orbits, and a seconds’ pendulum measures _time_ at the surface of our Earth. We feel assured that this law has never varied; but it is almost equally certain that it must have _begun_ to operate _under different conditions_ from those which obtain at this day.