ed. Matter does not
cease to be matter when modified by its contact with mind, as iron does
not cease to be iron when smelted and forged. A horseshoe is something
very different from a piece of iron ore; and a man may be acquainted with
the former without ever having seen the latter, or knowing what it is
like. But would Mr. Mill therefore say that the horseshoe is merely a
subjective affection of the skill of the smith--that it is not iron
modified by the workman, but the workman or his art impressed by iron?

If, indeed, Hamilton had said with Locke, that the primary qualities are
in the bodies themselves, whether we perceive them or no,[AF] he would
have laid himself open to Mr. Mill's criticism. But he expressly rejects
this statement, and contrasts it with the more cautions language of
Descartes, "ut sunt, vel saltem esse possunt."[AG] The secondary
qualities are mere affections of consciousness, which, cannot be
conceived as existing except in a conscious subject. The primary
qualities are qualities of body, as perceived in relation to the
percipient mind, _i.e._, of the phenomenal body perceived as in space.
How far they exist in the real body out of relation to us, Hamilton does
not attempt to decide.[AH] They are inseparable from our conception of
body, which, is derived exclusively from the phenomenon; they may or may
not be separable from the thing as it is in itself.

[AF] _Essay_, ii 8, Sec. 23.

[AG] _Reid's Works_, p. 839.

[AH] We have been content to argue this question, as Mr.
Mill himself argues it, on the supposition that Sir W.
Hamilton held that we are directly percipient of primary
qualities in external bodies. Strictly speaking, however,
Hamilton held that the primary qualities are immediately
perceived only in our organism as extended, and
inferred to exist in extra-organic bodies. The external
world is immediately apprehended only in its
secundo-primary character, as resisting our locomotive
energy. But as the organism, in this theory, is a
material _non-ego_ equally with the rest of matter, and as
to press this distinction would only affect the verbal
accuracy, not the substantial justice, of Mr. Mill's
criticisms, we have preferred to meet him on the ground
he has himself chosen. The same error, of supposing that
"presentationism" is identical with "noumenalism," and
"ph