Dr. Kroman's method of presentation is concise and lucid; the elements of logic occupy but some one hundred and four pages, and form a good introduction to the common phases of that science. But his psychology is, from our standpoint, more open to objection; or rather his philosophy. He says: "Unless we assume the law of causation, research is impossible; but assuming this, it is impossible to stop with states of consciousness, we must assume a subject and _real_ objects." What Dr. Kroman means by _real_ is seen from the following. "Our senses give us knowledge only of _properties_ of things, not of _things_. We do not perceive the apple, but only its form, color, etc. But all these sensations thus derived form an interconnected whole; and the law of causality forces us to the assumption of a _thing_ behind these sensory manifestations. Yet, our belief that we know this _thing in itself_ has only a practical value; in reality it is an unknown quantity. It is a single point, a nucleus, of which _direct and positive_ knowledge is unobtainable; yet exist it must if our assumption of the law of causation is to be upheld." Thus Dr. Kroman shows in an admirable manner how our everyday conceptual life _is_ formed; but it is the office of philosophy, in our view, to point out how this same conceptual life _should be_ formed. However, Dr. Kroman supplements this explanation—which we have much abbreviated—by considerations that lead one to believe that he seeks only to demonstrate the reality of existence and has collaterally accepted the doctrine of the independent, 'outside' thing in itself. We may refer our readers, regarding this question, to Prof. Mach's article in this number of _The Monist_. μκρκ EINLEITUNG IN DIE PSYCHOLOGIE NACH KRITISCHER METHODE. By _Paul Natorp_. Freiburg: J. C. Mohr. In this exhaustive monograph Dr. Paul Natorp does not deal with psychology itself, but proceeding from a number of novel points of view he opens up the road by which the principles of psychology may be reached. The author frankly assumes that psychology even as yet has not absolutely and clearly defined its own _fundamental problem_, and that this is chiefly the reason why we still disagree concerning the significance and value of many of the results of psychology. Before we approach the solution of the special problems, psychology _itself_ must be laid down as a problem. The author, therefore, in the first part of his introductory task has sought to indicate the _objects_ of psychology,—namely, what it will and rationally can pursue; and in the second part, he points out, the only correct _method_ according to which psychology can accomplish its aims.