ed a much more perfect conception
than he who possessed touch alone without vision. But of course our
touchless man would be devoid of any notion of resistance; and hence
space, for him, would be altogether geometrical and devoid of body.

And here another curious consideration arises, what likeness, if
any, would there be between the visual space of the one man, and the
tangible space of the other?

Berkeley, as we have seen (in the eighth proposition), declares that
there is no likeness between the ideas given by sight and those given
by touch; and one cannot but agree with him, so long as the term ideas
is restricted to mere sensations. Obviously, there is no more likeness
between the feel of a surface and the colour of it, than there is
between its colour and its smell. All simple sensations, derived
from different senses, are incommensurable with one another, and only
gradations of their own intensity are comparable. And thus so far as
the primary facts of sensation go, visual figure and tactile figure,
visual magnitude and tactile magnitude, visual motion and tactile
motion, are truly unlike, and have no common term. But when Berkeley
goes further than this, and declares that there are no "ideas" common
to the "ideas" of touch and those of sight, it appears to me that he
has fallen into a great error, and one which is the chief source of
his paradoxes about geometry.

Berkeley in fact employs the word "idea" in this instance to denote
two totally different classes of feelings, or states of consciousness.
For these may be divided into two groups: the primary feelings,
which exist in themselves and without relation to any other, such as
pleasure and pain, desire, and the simple sensations obtained through
the sensory organs; and the secondary feelings, which express those
relations of primary feelings which are perceived by the mind; and the
existence of which, therefore, implies the pre-existence of at least
two of the primary feelings. Such are likeness and unlikeness in
quality, quantity, or form; succession and contemporaneity; contiguity
and distance; cause and effect; motion and rest.

Now it is quite true that there is no likeness between the primary
feelings which are grouped under sight and touch; but it appears to me
wholly untrue, and indeed absurd, to affirm that there is no likeness
between the secondary feelings which express the relations of the
primary ones.

The relation of succession perceive