[29] _Ibid._ § 76 (1st ed.) [30] Compare _Principles of Psychology_, §§ 88, 95, 391, 401, 406. [31] _First Principles_, §§ 39–45. [32] _Principles of Psychology_, part vii. [33] _Social Statics_, chap. iii. [34] _Principles of Psychology_, § 531. [35] _First Principles_, § 34. [36] Only after the foregoing paragraphs were written, did the remark of a distinguished friend show me how certain words were misconstrued by the reviewer in a way that had never occurred to me as possible. In the passage referred to, I have said that sound-waves “finally die away in generating thermal undulations that radiate into space;” meaning, of course, that the force embodied in the sound-waves is finally _exhausted_ in generating thermal undulations. In common speech, the dying-away of a prolonged sound, as that of a church-bell, includes its gradual diminution as well as its final cessation. But rather than suppose I gave to the words this ordinary meaning, the reviewer supposes me to believe, not simply that the _longitudinal_ waves of air can pass, _without discontinuity_, into the _transverse_ waves of ether, but he also debits me with the belief that the one order of waves, having lengths measurable in feet, and rates expressed in hundreds per second, can, _by mere enfeeblement_, pass into the other order of waves, having lengths of some fifty thousand to the inch, and rates expressed in many billions per second! Why he preferred so to interpret my words, and that, too, in the face of contrary implications elsewhere (instance § 100), will, however, be manifest to every one who reads his criticisms. [37] Other examples of these amenities of controversy, in which I decline to imitate my reviewer, have already been given. What occasions he supplies me for imitation, were I minded to take advantage of them, an instance will show. Pointing out an implication of certain reasonings of mine, he suggests that it is too absurd even for me to avow explicitly; saying:—“We scarcely think that even Mr. Spencer will venture to claim as a datum of consciousness the Second Law of Motion, with its attendant complexities of component velocities, &c.” Now any one who turns to Newton’s _Principia,_ will find that to the enunciation of the Second Law of Motion, nothing whatever is appended but an amplified re-statement—there is not even an illustration, much less a proof. And from this law, this axiom, this immediate intuition or “datum of consciousness,” Newton proceeds forthwith to draw those corollaries respecting the composition of forces which underlie all dynamics. What, then, must be thought of Newton, who explicitly assumes that which the reviewer thinks it absurd to assume implicitly?