But, with the admission of the visual intuition of space, the objection vanishes, and the argument is shorn of all its strength. This admission relieves the theory from the necessity of maintaining, that conceptions derived from touch are transmuted into the perceptions of sight. It attributes to the sight all that ever truly belongs to it, namely, the perception of colours out of one another; it provides the visual intuitions with an externality of their own--and the theory never demands that they should acquire any other; and it leaves to these visual intuitions the office of merely suggesting to the mind tactual impressions, with which they have been invariably associated in place. We say, _in place_; and it will be found that there is no contradiction in our saying so, when we shall have shown that it is the touch, and not the sight, which establishes a protensive interval between the organ and the sensations of vision. Visible extension, then, or the perception of colours external to colours, being admitted, Mr Bailey's argument, if he still adheres to it, must be presented to us in this form. He must maintain that the theory requires that the objects of touch should not only be suggested by the visual objects with which they have been associated, but that they should actually be _seen_. And then he must maintain that no power of association can enable us to see an object which can only be touched--a position which, certainly, no one will controvert. The simple answer to all which, is, that we never do see tangible objects--that the theory never requires we should, and that no power of association is necessary to account for a phenomenon which never takes place. We cannot help thinking, that not a little of the misconception on this subject which prevails in the writings of Mr Bailey, and, we may add, of many other philosophers, originates in the supposition that we identify vision with the eye in the mere act of seeing, and in their taking it for granted that sight of itself informs us that we possess such an organ as the eye. Of course, if we suppose that we know instinctively, or intuitively, from the mere act of seeing, that the eye is the organ of vision, that it forms a part of the body we behold, and is located in the head, it requires no conjurer to prove that we _must_ have an instinctive, or intuitive, knowledge of visible things as larger than that organ, and, consequently, as external to it. In this case, no process of association is necessary to account for our knowledge of the distance of objects. That knowledge must be directly given in the very function and exercise of vision, as every one will admit, without going to the expense of an octavo volume to have it proved.