To a plain unsophisticated man, a stranger to the subtleties of metaphysical thought, it appears quite inconceivable, when he is told that the existence of the visible and palpable scene before him should be converted into a problem of apparently invincible difficulty. Yet so it is. The metaphysician first carries off in triumph what are called its secondary qualities, as colour and heat, proving them to be no qualities of matter, but of mind, or the sensitive being. He next assails what had been pronounced to be its primary or essential qualities; the dark tangible mass that he had left behind is not suffered to retain its inert existence; extension, the power to fill space or resist pressure, what are these, he asks, but our own sensations or remembered sensations of touch, which have got associated, embodied together, agglomerated round some occult cause? What, after all, he exclaims, do we know of matter but as a _something_ which possesses certain influences over _us_?--a something which is utterly unrepresented to us by the senses. And now this word "substance," which formerly expressed a thing so well known, and every moment handled and looked at, is transformed to an invisible, intangible, imperceptible substratum--an unknown upholder of certain qualities, or, in more exact language, an unseen power clothing itself in _our_ attributes--an existence far more resembling what is popularly understood by spirit than by matter. At length, even this unseen substratum is drawn within the world of thought, and becomes itself mere thought. There is _no_ matter, there is no space, save what the mind creates for, and out of itself. Our man of simple apprehension, much bewildered, not at all convinced, breaks from the chain of sophistry, opens wide his eyes, and declares after all that "seeing is believing." We think so too.