volved in the succeeding sciences, while certain characteristic new concepts are added. Furthermore, jurisprudence, astronomy and medicine are not included in the classification, for they are applied sciences and "do not unfold their problems systematically, but are assigned them by the external circumstance of man's life."
The chapters following are devoted to the exposition of how the dominant concepts of the pure sciences of the hierarchy bear a functional relation to each other.
Princeton University.
The author undertakes to inquire into the concrete genesis of the ideational material, by analyzing its relation to the groups of histological elements and the psycho-neurological factors determining the nature of its development. On the basis of this analysis he advances a theory of 'ideative erethism,' as a substitute for the associationist theory, in so far as the latter touches upon the formation of ideas and the entire mechanism of reasoning (p. 19). This question concerning the formation of ideas is the capital one about mental life: the manner in which its progressive complexity is organized (p. 35). The character of this organization eludes us until we recognize the central reactions in mental phenomena as elements essential to the proper understanding of the latter. This does not mean that the formation of ideas is a merely histological matter; but it calls for a much closer analysis of the organic, emotive, and volitional,—the dynamic factors,—than is to be found in the static, structural theories of ideation.
Literary images are the more effective the more conditioned they are by a sense-analogy. The kinship of two ideas or two images results in their mutual reinforcement. The chance which a new idea has of incorporating itself in the mental life depends upon its capacity to gain a ready access, by emphasizing or calling forth the analogy between itself and the ideational material already acquired which it awakes to new life. The new idea, in making its way to a group of cells of 'composite specificity,' may qualitatively change the latter, but this re-formation would be impossible unless the two are analogous. The effect of an impression, 'exalted' by long duration, intensity, or repetition, may be so heightened as to spread itself over the whole field of consciousness; but if it is to take root and relate itself to the material already acquired, it must enter into groups possessing constitutive elements which are analogous to it. Again, two ideas, presented all at once, may cancel each other's effect; should they be analogous, however, they 'join hands' and are perceived coincidently. These three modes, stimulating mental activity,—the perceptible exaltation, coincidence, and re-formation of the thought-elements,aid thought to affirm itself in its differentiation and to pass beyond the acquired differentiations in the acquisition of new ones (pp. 53, 310). This, in brief,
