n could effect this conversion; that if we did not
originally see colours to be out of each other, and the points of the
same colour to be out of each other, we could never so see them; and
that his argument, when thus based on the negation of all original
visual extension, and on the supposition that the touch is the sole
organ of every species of externality, would remain invulnerable.

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