FRIEDRICH ADOLF TRENDELENBURG (1802-1872), one of the chief revivers of Aristotelian study in the present century, was born on November 30, 1802, at Eutin, near Lübeck. He received his education at the gymnasium of his native town and at the universities of Kiel, Leipsic, and Berlin, displaying from his earliest years an extra* ordinary industry and thirst for knowledge. He was intra, duced to philosophy by König, the rector of the gymnasium a Kantian ; and at Kiel he came under the influence of Reinhold and Von Berger, to the latter of whom, a follower of Schelling, some of his own most characteristic views may be traced. At Berlin he heard Hegel and Schleiermacher; but his university studies lay chiefly in the direction of classics and classical philology under Wachsmuth, Hermann, and Boeckh. The combination of the philosopher and the philologist, together with a defi-nitely historical turn of mind, is what is most distinctive of all Trendelenburg's work. He became more and more attracted to the study of Plato and Aristotle, and his doctor's dissertation, published in 1826, was an attempt to reach through Aristotle's criticisms a more accurate knowledge of the Platonic philosophy (Piatonis de Ldeis et Numeris Doctrina ex Aristotele Lllustrata). Recognizing the sphere in which his best life-work could be done, he declined the offer of a classical chair at Kiel, and accepted instead a post as tutor to the son of Herr von Nagler, postmaster-general, and an intimate friend of Altenstein, the enlightened minister of education in Prussia. He held this position for seven years (1826-33), occupying his leisure time with the preparation of a critical edition of Aristotle's De Anima, and conscientiously extending his knowledge in all directions. His acquaintance with Karl Ferdinand Becker, the philologist and scientific gram-marian, was of importance for his own views on the origin of the logical categories and the relation of thought to language. In 1833 Trendelenburg was appointed extra-ordinary professor in Berlin, and four years later he was advanced to an ordinary professorship. During nearly forty years he proved himself markedly successful as an academical teacher, treating in turn all the usual philo-sophical disciplines, besides holding more select classes for the study of Aristotle with advanced students. During the greater part of that time he had also to examine in philo-sophy and pedagogics all candidates for the scholastic pro-fession in Prussia. He died on the 24th of January 1872.

It was with a view to the philosophical preparation in the gymnasia that he published (1836) his Elemente, Logices Aristo-telicse. This useful little book contains a selection of passages from the Organon, giving in a connected form the substance of Aristotle's logical doctrine. The Greek text is furnished with a Latin transla-tion and notes, and at a later date Trendelenburg supplemented this book with further explanations for the use of teachers (Erläuterungen zu den Elementen der aristotelischen Logik. 1842). The Elementa has passed through eight editions, and the Erläuter-ungen through three. In 1840 appeared the first of his important works, which, under the modest title of Logische Untersuchungen, develops a coherent philosophical theory, besides acutely criticiz-ing other standpoints, and in particular the then dominant Hegelian system. The Logische Untersuchungen were, indeed, an important factor in the reaction against Hegel which set in about that time in Germany. Two articles written by Trendelenburg in the controversy which ensued were republished separately, under the title Die logische Frage in Hegel's System (1843). A second and en-larged edition of the Logische Untersuchungen appeared in 1862, and a third in 1870. In 1846 he published the first volume of his "Historical Contributions to Philosophy" (Historische Beiträge zur Philosophie), containing a history of the doctrine of the cate-gories, which forms a pendant to his own elaboration of the same subject in the Logische Untersuchungen. A second volume of the " Historical Contributions " appeared in 1855, and a third in 1867, consisting of detached essays on points of interest in the history of philosophy. A number of these are papers originally read before the Prussian Academy of the Sciences, of which Trendelenburg was made a member in 1846. He was secretary of the philosophico-historical section from 1847 till 1871, and devoted much of his valuable time to the duties devolving upon him. A number of his papers dealing with non-philosophical—mainly with national and educational—subjects have been collected in his Kleine Schriften (2 vols., 1871). In I860 the second of his larger works appeared, Naturrecht auf dem Grunde der Ethik (second enlarged edition, 186S). In 1865 Trendelenburg became involved in a controversy with Kuno Fischer on the interpretation of Kant's doctrine of space, which was carried on with no little acrimony for a number of years. The war of 1870 drew from him a short treatise on the defects of international law,—Lücken im Völkerrecht. He had always had a deeply patriotic interest in the political development of Prussia, and through Prussia of Germany, and in the stormy times after 1848 had even acted for a short period as deputy to the Prussian chamber.
Trendelenburg's philosophizing is conditioned throughout by his loving study of Plato and Aristotle, whom he regards not as opponents but as building jointly on the broad basis of idealism. His own standpoint may almost be called a modern version of Aristotle thus interpreted. While denying the possibility of an absolute method and an absolute philosophy, as contended for by Hegel and others, Trendelenburg was emphatically an idealist in the ancient or Platonic sense; his whole work was devoted to the demonstration of the ideal in the real. But he maintained that the procedure of philosophy must be analytic, rising from the particular facts to the universal in which we fintl them explained. We divine the system of the whole from the part we know, just as from a torso we may reconstruct a work of art; but the process of reconstruction must, in the case of philosophy, remain approximative. Our position forbids the possibility of a final system. Instead, therefore, of constantly beginning afresh in speculation, it should be our duty to attach ourselves to what may be considered the permanent results of historic development. The classical expression of these results Trendelenburg finds mainly in the Platonico-Aristotelian system. The philosophical question is stated thus—How are thought and being united in knowledge ? how does thought get at being ? and how does being enter into thought ? Proceeding on the principle that like can only be known by like, Trendelenburg next reaches a doctrine peculiar to himself (though based upon Aristotle) which plays a central part in his speculations. Motion is the fundamental fact common to being and thought; the actual motion of the external world has its counterpart in the constructive motion which is involved in every instance of percep-tion or thought. From motion he proceeds to deduce time, space, and the categories of mechanics and natural science. These, being thus derived, are at once subjective and objective in their scope. It is true matter can never be completely resolved into motion, but the irreducible remainder may be treated like the irpdr-q v\r) of Aristotle as an abstraction which we asymptotically approach but never reach. The facts of existence, however, are not ade-quately explained by the mechanical categories. The ultimate interpretation of the universe can only be found in the higher category of End or final cause. Here Trendelenburg finds the dividing line between philosophical systems. On the one side stand those which acknowledge none but efficient causes,—which make force prior to thought, and explain the universe, as it were, a tergo. This may be called, typically, Democritism. On the other side stands the ;' organic " or teleological view of the world, which interprets the parts through the idea of the whole, and sees in the efficient causes
only the vehicle of ideal ends. This may be called in a wide sense
Platonism. Systems like Spinozism, which seem to form a third
class, neither sacrificing force to thought nor thought to force, yet
by their denial of final causes inevitably fall back into the Demo-
critic or essentially materialistic standpoint, leaving us with the
great antagonism of the mechanical and the organic systems of
philosophy. The latter view, wdiich receives its first support in
the facts of life, or organic nature as such, finds its culmination
and ultimate verification in the ethical world, which essentially
consists in the realization of ends. Trendelenburg's Naturrecht
may, therefore, be taken as in a manner the completion of his
system, his working out of the ideal as present in the real. The
ethical end is taken to be the idea of humanity, not in the abstract
as formulated by Kant, but in the context of the state and of
history. Law is treated throughout as the vehicle of ethical
requirements. In Trendelenburg's treatment of the state, as the
ethical organism in which the individual (the potential man) may
be said first to emerge into actuality, we may trace his nurture on
the best ideas of Hellenic antiquity. (A. SE.)