he refers to that notion of solidity which may be obtained by the
tactile sense, without the addition of any notion of resistance in the
solid object; as, for example, when the finger passes lightly over the
surface of a billiard ball.

Yet another source of difficulty in clearly understanding Berkeley
arises out of his use of the word "outness." In speaking of touch
he seems to employ it indifferently, both for the localization of
a tactile sensation in the sensory surface, which we really obtain
through touch; and for the notion of corporeal separation, which is
attained by the association of muscular and tactile sensations. In
speaking of sight, on the other hand, Berkeley employs "outness" to
denote corporeal separation.

When due allowance is made for the occasional looseness and ambiguity
of Berkeley's terminology, and the accessories are weeded out of the
essential parts of his famous Essay, his views may, I believe, be
fairly and accurately summed up in the following propositions:--

1. The sense of touch gives rise to ideas of extension, figure,
magnitude, and motion.

2. The sense of touch gives rise to the idea of "outness," in the
sense of localization.

3. The sense of touch gives rise to the idea of resistance, and thence
to that of solidity, in the sense of impenetrability.

4. The sense of touch gives rise to the idea of "outness," in the
sense of distance in the third dimension, and thence to that of space,