Professor Sidgwick’s defence of the Lockian view (_Philosophy: its Scope and Relations_, p. 63 ff.) seems to me to ignore the point at issue. namely, that in any sense in which “secondary” qualities get their meaning from the content of sensation, primary qualities do the same. The whole point is that the sensation is not merely (as process) the _occasion_ of our cognition of, _e.g._, hardness or softness, but also (as content) furnishes the very meaning of “hard” or “soft.” Cf. with what follows, _Appearance and Reality_, chap. 1. Footnote 79: The former alternative is that of scholasticism; in modern science the latter has been more or less consciously adopted by those thinkers who retain the notion of substances. The various qualities are on this view consequences of the relations in which each substance stands (_a_) to other interacting substances, and (_b_) in particular to the unknown substratum of our “consciousness.” Footnote 80: See chaps. 1 and 2 of bk. i. of his _Metaphysic_. Footnote 81: The reader who desires to study Kant’s doctrine in detail may begin by taking up Kant’s own _Prolegomena to the Study of any future Metaphysic_, which may be profitably consulted even by those who find the _Critique of Pure Reason_ too diffuse and technical. The latest and cheapest translation is that included in the Open Court Publishing Co.’s series of Philosophical Classics. Footnote 82: “Arbitrarily” because it is, as all recent psychology insists, the direction of our attention which determines _what_ qualities shall be presented together, and thus become “associated.” Footnote 83: In Psychology this comes out in the rejection by the best recent writers of the whole associationist account of the process of perception, according to which the perception of a thing as a whole was taken to mean the actual presence in sensation of one of its qualities _plus_ the reinstatement by association of the “ideas” of the others. For the modern doctrine of the perception of a whole, as distinct from the mere perception of its constituent parts, consult Stout, _Analytic Psychology_, bk. i. chap. 3, or _Manual of Psychology_,^3 bk. i. chap. 3. Footnote 84: