ing and a clock ticking,
Professor Huxley should perceive from the appearance of candle and clock
that they had gone on burning and ticking during his absence, would he
doubt that they had likewise gone on producing the motions constituting
and termed light and sound, notwithstanding that no eyes or ears had
been present to see or hear? But if he did not doubt this, how could he
any more doubt that, although all sentient creatures suddenly became
eyeless and earless, the sun might go on shining, and the wind roaring,
and the sea bellowing as before?

Akin to the inadvertence which, as I presume to think, has led Professor
Huxley thus to misconceive _secondary_ qualities, is an inattention to
the differences between our ideas, or mental pictures, and the originals
whereof those pictures are copies, which seems to me seriously to
vitiate his reasoning with regard to _primary_ qualities. With admirable
perspicuity he shows[34] how it is that our notions of primary qualities
are formed; how the mind, by _localising_ on distinct points of the
sensory surface of the body its various, tactile sensations, obtains the
idea of extension, or space in two dimensions, of figure, number, and
motion: how the power, combined with consciousness of the power, of
moving the hand in all directions over any substance it is in contact
with, adds the idea of geometrical solidity, or of space in three
dimensions: how the ideas thus formed with the aid of the sense of touch
are confirmed by, and blended with, others derived from visual
sensations and muscular movements of the eye: and, finally, how the idea
of mechanical solidity, or impenetrability, arises from experience of
resistance to our muscular exertions. All these details, however,
interesting as they are, are nevertheless quite out of place. What we
are at present concerned with is the nature of the things themselves,
not the nature of our knowledge of them. No question that this latter is
purely mental. If figure, motion, and solidity were really, as Professor
Huxley says, each of them nothing but a perception of the relation of
two or more sensations to one another, no question but that, since the
mind is the sole seat of perception, they could exist nowhere else. But
if all these suppositions be incorrect, if, as we have seen, there be in
matter and apart from mind, potentialities of producing sensations, it
follows that, in matter, and outside of mind, there must be relations
betw