We ask, then—does experience inform us, or does she not, that the sphere of sense falls within, and very considerably within, itself? But here it will be asked—what meaning do we attach to the expression, that sense falls within its own sphere? These words, then, we must first of all explain. Every thing which is apprehended as a sensation—such as colour, figure, hardness, and so forth—falls within the sentient sphere. To be a sensation, and to fall within the sphere of sense, are identical and convertible terms. When, therefore, it is asked does the sphere of sense ever fall within itself? this is equivalent to asking—do the senses themselves ever become sensations? Is that which apprehends sensations ever itself apprehended as a sensation? Can the senses be seized on within the limits of the very circle which they prescribe? If they cannot, then it must be admitted that "the sphere of sense never falls within itself, and consequently that an objective reality—i.e. a reality extrinsic to that sphere—can never be predicated or secured for any part of its contents. But we conceive that only one rational answer can be returned to this question. Does not experience teach us, that much if not the whole of our sentient nature becomes itself in turn a series of sensations? Does not the sight—that power which contains the whole visible space, and embraces distances which no astronomer can compute—does it not abjure its high prerogative, and take rank within the sphere of sense—itself a sensation—when revealed to us in the solid atom we call the eye? Here it is the touch which brings the sight within, and very far within, the sphere of vision. But somewhat less directly, and by the aid of the imagination, the sight operates the same introtraction (pardon the coinage) upon itself. It ebbs inwards, so to speak, from all the contents that were given in what may be called its primary sphere. It represents itself, in its organ, as a minute visual sensation, out of, and beyond which, are left lying the great range of all its other sensations. By imagining the sight as a sensation of colour, we diminish it to a speck within the sphere of its own sensations; and as we now regard the sense as for ever enclosed within this small embrasure, all the other sensations which were its, previous to our discovery of the organ, and which are its still, are built up into a world of objective existence, necessarily external to the sight, and altogether out of it's control. All sensations of colour are necessarily out of one another. Surely, then, when the sight is subsumed under the category of colour—as it unquestionably is whenever we think of the eye—surely all other colours must, of necessity, assume a position external to it; and what more is wanting to constitute that real objective universe of light and glory in which our hearts rejoice?
We can, perhaps, make this matter still plainer by reverting to our old illustration. Our first exposition of the question was designed to exhibit a general view of the case, through the medium of a dead symbolical figure. This proved nothing, though we imagine that it illustrated much. Our second exposition exhibited the illustration in its application to the living sphere of sensation in general; and this proved little. But we conceive that therein was foreshadowed a certain procedure, which, if it can be shown from experience to be the actual procedure of sensation in detail, will prove all that we are desirous of establishing. We now, then, descend to a more systematic exposition. of the process which (so far as our experience goes, and we beg to refer the reader to his own) seems to be involved. in the operation of seeing. We dwell chiefly upon the sense of sight, because it is mainly through its ministrations that a real objective universe is given to us. Let the circle A be the whole circuit of vision. We may begin by calling it the eye, the retina, or what we will. Let it be provided with the ordinary complement of sensations—the colours X Y Z. Now, we admit that these sensations cannot be extruded beyond the periphery of vision; and yet we maintain that, unless they be made to fall on the outside of that periphery, they cannot become real objects. How is this difficulty—this contradiction—to be overcome? Nature overcomes it, by a contrivance as simple as it is beautiful. In the operation of seeing, admitting the canvass or background of our picture to be a retina, or what we will, with a multiplicity of colours depicted upon it, we maintain that we cannot stop here, and that we never
