_as perceived_ is recognized as having no existence apart from
its relation to a percipient mind. Now, although physiologists are at
one with the philosophers thus far, it is to be feared that very
frequently they are in the same position as the above-mentioned
'uneducated men,' when it becomes needful to press still further into
the thicket. For after having distinguished the necessity of recognizing
a mind-element in any possible theory of perception, they forthwith
proceed to disregard this element when passing from the ground of
perception to that of thought. Although the ideas of matter, motion,
causation, and so on, are themselves as much the offspring of a thinking
mind, with its environment, as the perception of colour is a conceiving
of the percipient mind, with _its_ environment, these ideas are
inconsistently supposed to stand for equivalent realities of the
external world--to truly represent things that are virtually independent
of any necessary relation to mind. Or, as the case has recently been
well put by Principal Caird:

'You cannot get mind as an ultimate product of matter, for in the
very attempt to do so you have already begun with mind. The
easiest step of any such inquiry involves categories of thought,
and it is in terms of thought that the very problem you are
investigating can be so much as stated. You cannot start in your
investigations with a bare, self-identical, objective fact,
stripped of every ideal element or contribution from thought. The
least and lowest part of outward observation is not an independent
entity--fact _minus_ mind, and out of which mind may, somewhere or
other, be seen to emerge; but it is fact or object as it appears to
an observing mind, in the medium of thought, having mind or thought
as an inseparable factor of it. Whether there be such a thing as an
absolute world outside of thought, whether there be such things as
matter and material atoms existing in themselves before any mind
begins to perceive or think about them, is not the question before
us. If it were possible to conceive of such atoms, at any rate you,
before you begin to make anything of them, must think them; and you
can never, by thinking about atoms, prove that there is no such
thing as thought other than as an ultimate product of atoms. Before
you could reach thought or mind as a last result you must needs