NEW BOOKS. 593 basis. For "the content of consciousness is the thing-in-itself " ; being is in its essence consciousness ; and " our physical life and our psychical activity are only different functions of the same substantial cause ". Beitrdge zur Analyse der Empfindungen. Von Dr. E. MACH, Professor der Physik an der deutschen Universitat zu Prag. Mit 36 Abbildungen. Jena : Gustav Fischer, 1886. Pp. vi., 168. Ueber die Psycliophysik. Physikalische und erkenntnisstheoretische Be- traclitungen. Von Dr. ADOLF ELSAS, Privatdocenten der Physik an der Universitat zu Marburg. Marburg : N. G. Elwert, 1886. Pp. vii., 76. Prof. Mach's present series of papers continues his psychophysical work by investigations on the sense of space, of time and of tone. He here con- tends for a " principle of the complete parallelism of the psychical and physical " ; which may, if we like, be accepted merely as " a heuristic principle," but must in any case be postulated. His mode of conceiving this principle requires " proportionality of stimulus and sensation," and so determines the rejection of Fechner's logarithmic law (p. 38). It was, however, from the Elemente der Psychophysik, as he tells us, that he received, twenty-five years since, the most powerful impulse towards investigations such as these. The present researches are preceded and followed by sections dealing with the more general aspects of the author's work. Scientific conceptions, he holds, may be viewed as " economical means," that is, means of comprehending natural phenomena with the least expenditure of labour. He notes (p. 141) the resemblance of this view to that which is developed by Prof. W. James in his article on " The Sentiment of Eation- ality," in MIXD, Vol. iv. 317. Dr. Elsas, criticising Fechner's law in detail from the point of view of mathematical physics, arrives at the conclusion that it is not correctly deduced. Further, he contends that a " psychophysics," in Fechner's sense, is impossible. Feeling is in no way an object of scientific know- ledge ; " it does not belong to nature ; it has for the mathematical physicist no reality ; it does not allow itself to be treated mathematically as a quantity ". Leo Hebrceus, tin jiidischer Philosoph der Renaissance; sein Leben, seine Werke und seine Lehren. Von Dr. B. ZiMMELS. Breslau : W. Koebner, 1886. Pp. 120. This is an account of the Jewish philosopher Don Judah Abarbanel (b. 1460-3, d. 1520-35), better known as Leo Hebrseus, whose Dialogues on Love, written originally in Italian and afterwards translated into French, Spanish, Latin and Hebrew, have some importance in the history of the Platonism of the Renaissance. An Introduction on " Leo Hebrseus and his Times " (pp. 1-15) is followed by sections dealing separately with his life (pp. 16-47), which was even more eventful than the lives of phi- losophers of the period usually were ; his works (pp. 48-66) ; and his philosophical doctrines (pp. 67-120). Leo was one of the philosophers who tried to reconcile Plato and Aristotle. According to Munk, it was " under the auspices of the Kabbalah " that this reconciliation was attempted ; but the author contends that with Leo "Kabbalah" only means "tradition" (as embodied in the Talmud and other post-biblical writings). From the frequency of the expression " intellectual love " in Leo's dialogues, he con.- jectures an influence on Giordano Bruno and Spinoza (see note, pp. 74-9). In distinction from the Jewish Scholastics, who tried to show everywhere the identity of orthodox Judaism and Aristotelian philosophy, Leo made a division between faith and scientific reason ; maintaining the equal truth of both, each in its cwn sphere (pp. 81-3).
