CRITICAL NOTICES: Lewis's "A Text-Book of Mental Diseases." Mercier's "Sanity and Insanity"; Jones's "Elements of Logic as a Science of Propositions"; Coupland's "The Gain of Life and other Essays." ON THE UTILITARIAN FORMULA. By _James Sutherland_. _The Origin of Music._ This article is intended as a postscript to Mr. Spencer's essay on "The Origin and Function of Music," included in his _Essays, Scientific, Political, and Speculative_, of which he is preparing a final edition. It is a reply to Mr. Darwin, who supposes music to have originated from a particular class of vocal noises, the amatory class, instead of, as Mr. Spencer asserts, its being derived from the sounds which the voice emits under excitement, eventually gaining this or that character according to the kind of excitement. After considering various objections by Mr. Edmund Gurney and others, Mr. Spencer concludes: "The origin of music as the developed language of motion seems to be no longer an inference but simply a description of the fact." Mr. James Sully deals with Differentiation, Assimilation, and Association as the intellectual constituents in the process of Mental Elaboration. Differentiation is considered first as a process of marking off, by means of special adjustments of attention, particular sensations; followed by Discrimination, which involves change of psychical state, the dependence of mental life on which has been formulated as the Law of Relativity. Assimilation, described as a mode of unification or integration, is treated of under the headings, _Psychological Nature of Likeness_; _Automatic Assimilation_; _Recognition_; and _Transition to Comparative Assimilation_. Association is the "process of psychical combination or integration which binds together presentative elements occurring together or in immediate succession." This supposes _Retention_ or the tendency of a sensation to persist, and _Reproduction_, or the reappearance "in consciousness" of the impression under a new representative form. The three processes of Differentiation, Assimilation, and Association do not follow each other, but are closely interconnected.