=Unjustifiable Materialism.=—No wonder the author finds himself compelled to admit that to some readers “such an assumption will seem like the most unjustifiable _à priori_ materialism.” The discussion of ‘the self’ might be supposed to present insuperable difficulties, but they are disposed of, and, says our author, “The logical conclusion seems to be that the _states of consciousness are all that psychology needs to do her work with. Metaphysics or theology may prove the soul to exist, but for psychology the hypothesis of such a substantial principle of unity is superfluous._” That is to say, the important personage which I call _I_, _myself_, need be no more than perpetually shifting states of consciousness effected by the brain; and the sameness or identity of person, which seems at first sight the one bit of solid ground in a shifting morass, rests upon no more than the fact that the brain may be conscious of the same objects to-day that it was conscious of years ago. =Psychology, ‘A Phrase of Diffidence.’=—But, after proving with great clearness and power through a considerable volume[2] that all the phenomena of intelligent life _may_ have their sole source in the physical brain, Professor James concludes—“When, then, we talk of psychology as a natural science we must not assume that that means a sort of psychology that stands at last on solid ground. It means just the reverse; it means a psychology particularly fragile and into which the waters of metaphysical criticism leak at every joint, a psychology all of whose elementary assumptions and data must be reconsidered in wider connections and translated into other terms. It is, in short, a phrase of diffidence and not of arrogance, and it is indeed strange to hear people talk triumphantly of the ‘New Psychology’ and write ‘Histories of Psychology’ when into the real elements and forces, which the word covers, not the first glimpse of clear insight exists. A string of raw facts, a little gossip and wrangle about opinions, a little classification and generalisation on the mere descriptive level ... but not a single law ... not a single proposition from which any consequence can causally be deduced.” This is soothing, and we close Professor James’s book with satisfaction; but the pity of it is that all the ‘new’ psychologists are not so modest as the Professor,—some of them are, may we venture to say so, not a little arrogant: what is more, the student who goes carefully through this text-book of psychology is only too likely to consider that the author has proved his case—that psychology is a ‘natural science,’ ‘and it is,’ like Peter Bell’s primrose, ‘nothing more’—up to the hilt, and he is not likely to go through a process of reconversion at the last page.