Swiss Baden, where the beach of the Limmat is almost wholly composed of brecciated limestones, I began to examine them thoughtfully; and perceived, in the end, that they were, one and all, knots of as rich mystery as any poor little human brain was ever lost in. That piece of agate in your hand, Mary, will show you many of the common phenomena of breccias; but you need not knit your brows over it in that way; depend upon it, neither you nor I shall ever know anything about the way it was made, as long as we live. DORA. That does not seem much to depend upon. L. Pardon me, puss. When once we gain some real notion of the extent and unconquerableness of our ignorance, it is a very broad and restful thing to depend upon: you can throw yourself upon it at ease, as on a cloud, to feast with the gods. You do not thenceforward trouble yourself,--nor any one else,--with theories, or the contradiction of theories; you neither get headache nor heart-burning and you nevermore waste your poor little store of strength or allowance of time. However, there are certain facts, about this agate-making, which I can tell you; and then you may look at it in a pleasant wonder as long as you like, pleasant wonder is no loss of time. First, then, it is not broken freely by a blow; it is slowly wrung, or ground, to pieces. You can only with extreme dimness conceive the force exerted on mountains in transitional states of movement. You have all read a little geology; and you know how coolly geologists talk of mountains being raised or depressed. They talk coolly of it, because they are accustomed to the fact; but the very universality of the fact prevents us from ever conceiving distinctly the conditions of force involved. You know I was living last year in Savoy; my house was on the back of a sloping mountain, which rose gradually for two miles behind it; and then fell at once in a great precipice toward Geneva, going down three thousand feet in four or five cliffs, or steps. Now that whole group of cliffs had simply been torn away by sheer strength from the rocks below, as if the whole mass had been as soft as biscuit. Put four or five captains' biscuits on the floor, on the top of one another; and try to break them all in half, not by bending, but by holding one half down, and tearing the other halves straight up;--of course you will not be able to do it, but you will feel and comprehend the sort of force needed. Then, fancy each captains' biscuit a bed of rock, six or seven hundred feet thick; and the whole mass torn straight through; and one half heaved up three thousand feet, grinding against the other as it rose,--and you will have some idea of the making of the Mont Saleve. MAY. But it must crush the rocks all to dust!