If Zeller’s semi-Hegelian theory of history does scant justice to the variety and complexity of causes determining the evolution of philosophy, it also draws away attention from the ultimate elements, the matter, in an Aristotelian sense, of which that evolution consists. By this I mean the development of particular ideas as distinguished from the systems into which they enter as component parts. Often the formation of a system depends on an accidental combination of circumstances, and therefore cannot be brought under any particular law of progress, while the ideas out of which it is constructed exhibit a perfectly regular advance on the form under which they last appeared. Others, again, are characterised by a remarkable fixity which enables them to persist unchanged through the most varied combinations and the most protracted intervals of time. But when each system is regarded as, so to speak, an organic individual, the complete and harmonious expression of some one phase of thought, and the entire series of systems as succeeding one another in strict logical order according to some simple law of evolution, there will be a certain tendency to regard the particular elements of each as determined by the character of the whole to which they belong, rather than by their intrinsic nature and antecedent history. And I think it is owing to this limitation of view that Zeller has not illustrated, so fully as could be desired, the subtler references by which the different schools of philosophy are connected with one another and also with the literature of their own and other times. An interesting example of the process on which I have just touched is offered by the reappearance and further elaboration of some most important Greek ideas in modern philosophy. In the concluding chapter of this work I have attempted to indicate the chief lines along which such a transmission may be traced. The subject is one which has hitherto been unduly neglected. No critic would be justified in describing the speculative movement of the nineteenth century without constant reference to the metaphysicians and moralists of the two preceding centuries. Yet the dependence of those thinkers on the schools of antiquity is hardly less intimate than our dependence on Spinoza and Hume. Nevertheless, in no work that I am acquainted with has this circumstance been used to elucidate the course pursued by modern thought; indeed, I may say that the persistence of Hellenic ideas down to the most recent times has not been fully recognised by any scholar except Prof. Teichmüller, who has particularly devoted his attention to the history of conceptions as distinguished from the history of systems.