is
indissolubly associated the idea of _externality_. It is true that
extension and resistance are only qualities, but it is equally true that
they are qualities of something, and of something which is external to
ourselves. Let any one attempt to conceive of extension without
something which is extended, or of resistance apart from something which
offers resistance, and he will be convinced that we can never know
qualities without knowing substance, just as we can not know substance
without knowing qualities. This, indeed, is admitted by Mr. Mill.[245]
And if this be admitted, it must certainly be absurd to speak of
substance as something "unknown." Substance is known just as much as
quality is known, no less and no more.

[Footnote 244: Hamilton, "Lectures," vol. 1. p. 288.]

[Footnote 245: "Logic," bk. i. ch. iii. Sec. 6.]

We remark, in conclusion, that if the testimony of consciousness is not
accepted in all its integrity, we are necessarily involved in the
Nihilism of Hume and Fichte; the phenomena of mind and matter are, on
analysis, resolved into an absolute nothingness--"a play of phantasms in
a void."[246]

(ii.) We turn, secondly, to the _Materialistic School_ as represented by
Aug. Comte.

The doctrine of this school is that all knowledge is limited to
_material_ phenomena--that is, to appearances _perceptible to sense_. We
do not know the essence of any object, nor the real mode of procedure of
any event, but simply its relations to other events, as similar or
dissimilar, co-existent or successive. These relations are constant;
under the same conditions, they are always the same. The constant
resemblances which link phenomena together, and the constant sequences
which unite them, as antecedent and consequent, are termed _laws_. The
laws of phenomena are all we know respecting them. Their essential
nature and their ultimate causes, _efficient_ or _final_, are unknown
and inscrutable to us.[247]

[Footnote 246: Masson, "Recent British Philos.," p. 62.]

[Footnote 247: See art. "Positive Philos. of A. Comte," _Westminster
Review_, April, 1865, p. 162, Am. ed.]

It is not our intention to review the system of philosophy propounded by
Aug. Comte; we are now chiefly concerned with his denial of all
causation.

1. _As to Efficient Causes_.--Had Comte contented himself with the
assertion that causes lie beyond the field of sensible observation, and
that inductive science can not carry us beyond the rel