Now, however, for once, look at a piece of marble carefully, and think about it. You see this is one side of the fault; the other side is down or up, nobody knows where; but, on this side, you can trace the evidence of the dragging and tearing action. All along the edge of this marble, the ends of the fibers of the rock are torn, here an inch, and there half an inch, away from each other; and you see the exact places where they fitted, before they were torn separate: and you see the rents are now all filled up with the sanguine paste, full of the broken pieces of the rock; the paste itself seems to have been half melted, and partly to have also melted the edge of the fragments it contains, and then to have crystallized with them, and round them. And the brecciated agate I first showed you contains exactly the same phenomena; a zoned crystallization going on amidst the cemented fragments, partly altering the structure of those fragments themselves, and subject to continual change, either in the intensity of its own power, or in the nature of the materials submitted to it;--so that, at one time, gravity acts upon them, and disposes them in horizontal layers, or causes them to droop in stalactites; and at another, gravity is entirely defied, and the substances in solution are crystallized in bands of equal thickness on every side of the cell. It would require a course of lectures longer than these (I have a great mind,--you have behaved so saucily--to stay and give them) to describe to you the phenomena of this kind, in agates and chalcedonies only,--nay, there is a single sarcophagus in the British Museum, covered with grand sculpture of the 18th dynasty, which contains in magnificent breccia (agates and jaspers imbedded in porphyry), out of which it is hewn, material for the thought of years; and record of the earth-sorrow of ages in comparison with the duration of which, the Egyptian letters tell us but the history of the evening and morning of a day.