The materialist, secure in the certainty of sensation, mocks at fine-spun theories, at star-gazers and dreamers, and believes that his life is solid, that he at least takes nothing for granted, but knows where he stands, and what he does. Yet how easy it is to show him, that he also is a phantom walking and working amid phantoms, and that he need only ask a question or two beyond his daily questions, to find his solid universe growing dim and impalpable before his sense. The sturdy capitalist, no matter how deep and square on blocks of Quincy granite he lays the foundations of his banking-house, or Exchange, must set it, at last, not on a cube corresponding to the angles of his structure, but on a mass of unknown materials and solidity, red-hot or white-hot, perhaps at the core, which rounds off to an almost perfect sphericity, and lies floating in soft air, and goes spinning away, dragging bank and banker with it at a rate of thousands of miles the hour, he knows not whither,--a bit of bullet, now glimmering, now darkling through a small cubic space on the edge of an unimaginable pit of emptiness. And this wild balloon, in which his whole venture is embarked, is a just symbol of his whole state and faculty. One thing, at least, he says is certain, and does not give me the headache, that figures do not lie; the multiplication table has been hitherto found unimpeachable truth; and, moreover, if I put a gold eagle in my safe, I find it again to-morrow;--but for these thoughts, I know not whence they are. They change and pass away. But ask him why he believes that an uniform experience will continue uniform, or on what grounds he founds his faith in his figures, and he will perceive that his mental fabric is built up on just as strange and quaking foundations as his proud edifice of stone.