Moreover, it may be noted that the support which this form of idealism
sometimes receives from an argument which uses the terms 'inside' and
'outside' the mind is unmerited. At first sight it seems a refutation
of the plain man's view to argue thus: 'The plain man believes the
spatial world to exist whether any one knows it or not. Consequently,
he allows that the world is outside the mind. But, to be known, a
reality must be inside the mind. Therefore, the plain man's view
renders knowledge impossible.' But, as soon as it is realized that
'inside the mind' and 'outside the mind' are metaphors, and,
therefore, must take their meaning from their context, it is easy to
see that the argument either rests on an equivocation or assumes the
point at issue. The assertion that the world is outside the mind,
being only a metaphorical expression of the plain man's view, should
only mean that the world is something independent of the mind, as
opposed to something inside the mind, in the sense of dependent upon
it, or mental. But the assertion that, to be known, a reality must be
inside the mind, if it is to be incontestably true, should only mean
that a reality, to be apprehended, must really be object of
apprehension. And in this case 'being inside the mind', since it only
means 'being object of apprehension', is not the opposite of 'being
outside the mind' in the previous assertion. Hence, on this
interpretation, the second assertion is connected with the first only
apparently and by an equivocation; there is really no argument at all.
If, however, the equivocation is to be avoided, 'inside the mind' in
the second assertion must be the opposite of 'outside the mind' in the
first, and consequently the second must mean that a reality, to be
known, must be dependent on the mind, or mental. But in that case the
objection to the plain man's view is a _petitio principii_, and not an
argument.

Nevertheless, the tendency to think that the only object or, at least,
the only direct object of the mind is something mental still requires
explanation. It seems due to a tendency to treat self-consciousness as
similar to consciousness of the world. When in reflection we turn our
attention away from the world to the activity by which we come to know
it, we tend to think of our knowledge of the world as a reality to be
apprehended similar to the world which we apprehended prior to
reflection. We thereby implicitly treat this knowledge as som