Their peculiarities determine what is the nature of the outside world which we construct.

It is the similarity in the organs of sense and in the perceptive faculty of all normal human beings which makes the outside world the same, or _practically_ the same, for them all.

To return to the old analogy, it is as if two telephone exchanges had very nearly identical groups of subscribers.
In this case a wire between the two exchanges would soon convince the imprisoned clerks that they had something in common and peculiar to themselves.

That conviction corresponds in our comparison to the recognition of other consciousness." I suggest that this extract be read over carefully, not once but several times, and that the reader try to make quite clear to himself the position of the clerk in the telephone exchange, _i.e._ the position of the mind in the body, as depicted by Professor Pearson, before recourse is had to the criticisms of any one else.

One cannot find anywhere better material for critical philosophical reflection.
As has been seen, our author accepts without question, the psychological doctrine that the mind is shut up within the circle of the messages that are conducted to it along the sensory nerves, and that it cannot directly perceive anything truly external.