whose theory of
external perception is identical with that which Mr. Mill would force on
Hamilton himself, Hamilton says: "On the general doctrine, however, of
these philosophers, both classes of qualities, as known, are confessedly
only states of our own minds; and while we have no right from a
subjective affection to infer the existence, far less the corresponding
character of the existence, of any objective reality, it is evident that
their doctrine, if fairly evolved, would result in a dogmatic or in a
sceptical negation of the primary no less than of the secondary qualities
of body, as more than appearances in and for us."[AD] It is astonishing
that Mr. Mill, who pounces eagerly on every imaginable instance of
Hamilton's inconsistency, should have neglected to notice this, which, if
his criticism be true, is the most glaring inconsistency of all.

[AD] _Reid's Works_, p. 840.

But Hamilton continues: "It is therefore manifest that the fundamental
position of a consistent theory of dualistic realism is--that our
cognitions of Extension and its modes are not wholly ideal--that although
Space be a native, necessary, _a priori_ form of imagination, and so
far, therefore, a mere subjective state, that there is, at the same time,
competent to us, in an _immediate_ perception of external things, the
_consciousness_ of a really existent, of a really objective, _extended_
world." Here we have enunciated in one breath, first the subjectivity of
space, which is the logical basis of the relative theory of perception;
and secondly, the objectivity of the extended world, which is the logical
basis of the distinction between primary and secondary qualities. It is
manifest, therefore, that Hamilton had not, as Mr. Mill supposes, ceased
to hold the one theory when he adopted the other.[AE]

[AE] See _Examination_, p. 28.

The key to all this is not difficult to find. It is simply that
_objective existence_ does not mean existence _per se_; and that a
_phenomenon_ does not mean a mere mode of mind. Objective existence is
existence _as an object_, in perception, and therefore in relation; and a
phenomenon may be material, as well as mental. The thing _per se_ may be
only the unknown cause of what we directly know; but what we directly
know is something more than our own sensations. In other words, the
phenomenal effect is material as well as the cause, and is, indeed, that
from which our primary conceptions of matter are deriv