Benno Erdmann, of Bonn, a man profoundly learned in historical philosophy, who has advanced by important contributions, not unrelated, two such different sciences as experimental psychology and modern logic, in which he is an acknowledged master.
This session promised well from the start. The audience was representative in more ways than one. In addition to the professional philosophers, a number of remarkable men of science were present. In the front row, for instance, sat Svante Arrhenius, of Stockholm, physical chemist, famous for his mathematical and experimental contributions to the theory of solutions and speaker for cosmical physics, and Ludwig Boltzmann, of Vienna, mathematical physicist, distinguished especially for his work in the kinetic theory of gases, who represented applied mathematics in the program of the congress. Scattered through the audience were many eminent leading representatives of both the physical and mental sciences. Among Americans on the front were Loeb in biology and Cattell in psychology, both eminent specialists actively interested in scientific methods, both having applied exact methods with conspicuous success, albeit in very different ways, to the investigation of phenomena of life and mind. This is not the place to attempt a summary of the leading addresses, both delivered in German. Suffice it to point out that Ostwald presented a classification of the sciences professedly based on the empirical standpoint of energetics, and bearing but slight resemblance to the elaborate scheme which shaped the program of the congress. Erdmann attacked the subject from a frankly à priori point of view, arguing for the position which has recourse to a generating principle of logical necessity. Among those who took part in the open discussion were Boltzmann, Hoeffding, Ormond, Miss Calkins, etc., and the chief speakers again in reply.
In the section for ethics the speakers were Professor William B. Sorley, of Cambridge, able philosophical moralist, keen critic of the ethics of naturalism, who has made sound learning, astuteness and vigor of mind tell also in the study of the more vital questions of practice, and Professor Paul Hensel, of the University of Erlangen, philosophical scholar and critic, a gifted student of ethical theory and interpreter of ethical ideals in literature. The first address in the esthetics section was made by Dr. Henry Rutgers Marshall, of New York, a successful architect by profession, a philosopher by instinct and performance, distinguished as a philosophical student of psychology and a psychological student of esthetics, who has made interesting contributions to the analytical and genetic aspects of both sciences. The second speaker was Professor Max Dessoir, of the University of Berlin, erudite historian of German psychology in all its ramifications, himself a philosopher, psychologist and esthetician.
And so one might run through the long program, apart from a fortunate limitation of space and an unfortunate but inevitable igno-
