NEW BOOKS. 633

it is only in ancient and modern times that the attempt lias been made to work out a practical philosophy on purely philosophical grounds. The Ethics of classical antiquity has permanent interest (1) because, scientifi- cally, it created moral, social and political philosophy, and stated all possible views of the end of life, (2) because of its " ideal direction ". Its idealism consists in its telling men to seek as their end both personal per- fection and the perfection of the political society in which they live. This idealism, however, has a " naturalistic element " ; perfection being held to consist entirely in the unfolding of natural dispositions. The recognition that the highest end of all is conformity to a binding " moral law " is absent. Hence ancient Ethics, in its view of the destination of man, has not attained complete " spirituality ". Christianity, deriving the conception of moral law from Judaism, replaced ancient " naturalism " by " spiritual- ism". In the Middle Ages, spiritualism was exaggerated into a dualism that placed the spirit in antagonism to reality. In modern times, the real regained its rights ; and at the same time there has been a constant effort to reconcile ancient naturalism with Christian spiritualism. All the branches of practical philosophy have also been studied more thoroughly and completely, "so that now for the first time a true philosophy of human things, of human interests and human ideals as a whole, has been created ". Ueber die wahren Ursachen. Eine Studie von Dr. S. STRICKER, Universitats- Professor in Wien. Wien : A. Holder, 1887. Pp. 60. This investigation of what is meant by " cause " was started by Hume's doctrine of causality, and proceeds on the basis of the psychological results arrived at by the author in his Studien iiber die Bewegungsvorstellungen (1882), here briefly recapitulated. The perception of motion, he con- cluded in the former work,' cannot have been acquired by the fusion of mere passive sensations, but always depends on a determination of action or incipient action of muscles. In volition, muscular movement follows immediately upon innervation of motor nerves, and is felt as in direct quan- titative relation (though not strictly proportional) to the intensity of the felt innervation that precedes it. It is to this type that all motion is primi- tively referred. External motions, since their perception is involuntary, are referred to a will external to that of the percipient ; those that do not proceed from other men or from animals being referred to invisible living beings. For will, physical science substitutes " force," which is merely will depersonalised ; and, by a speculative extension of the conception of force, the apparently spontaneous beginnings of action in volition are themselves traced back to pre-existing forces. The search for causes,, therefore, is grounded in our internal experience. It is not to be explained, as Hume explains it, by observed customary conjunctions of events in the external world ; but is the reference of an event which, as soon as perceived, deter- mines in us motor feelings, to the type of the production of such feelings which exists in ourselves. And in any particular case we seek the true cause of an event either by active experiment or by comparison with pre- vious active experiments of which we possess the results in the form of the "potential knowledge" that constitutes "common-sense": we do not simply call any customary antecedent the " cause " of its consequent. A " true cause " is the " origin " or " source " of matter or motion (" Ursache " = " Ursprung " or " Urquelle "). As the "cause" of any particular portion of matter is that portion of matter pre-existing somewhere else, so the "cause" of the force or motion possessed by any portion of matter is that same quantity of force or motion possessed by some other portion of matter. The law of causality is therefore identical with the "law of con- servation" of physics. (The author promises to defend, in a second part of 41