thought of Plato, of Aristotle, and of the heroes of modern philosophy is ever proving anew its fructifying power.  Nowhere do we find such instructive errors as in the sphere of philosophy; nowhere is the new so essentially a completion and development of the old, even though it deem itself the whole and assume a hostile attitude toward its predecessors; nowhere is the inquiry so much more important than the final result; nowhere the categories “true and false” so inadequate.  The spirit of the time and the spirit of the people, the individuality of the thinker, disposition, will, fancy—­all these exert a far stronger influence on the development of philosophy, both by way of promotion and by way of hindrance, than in any other department of thought.  If a system gives classical expression to the thought of an epoch, a nation, or a great personality; if it seeks to attack the world-riddle from a new direction, or brings us nearer its solution by important original conceptions, by a subtler or a simpler comprehension of the problem, by a wider outlook or a deeper insight; it has accomplished more than it could have done by bringing forward a number of indisputably correct principles.  The variations in philosophy, which, on the assumption of the unity of truth, are a rock of offense to many minds, may be explained, on the one hand, by the combination of complex variety and limitation in the motives which govern philosophical thought,—­for it is the whole man that philosophizes, not his understanding merely,—­and, on the other, by the inexhaustible extent of the field of philosophy.  Back of the logical labor of proof and inference stand, as inciting, guiding, and hindering agents, psychical and historical forces, which are themselves in large measure alogical, though stronger than all logic; while just before stretches away the immeasurable domain of reality, at once inviting and resisting conquest.  The grave contradictions, so numerous in both the subjective and the objective fields, make unanimity impossible concerning ultimate problems; in fact, they render it difficult for the individual thinker to combine his convictions into a self-consistent system.  Each philosopher sees limited sections of the world only, and these through his own eyes; every system is one-sided.  Yet it is this multiplicity and variety of systems alone which makes the aim of philosophy practicable as it endeavors to give a complete picture of the soul and of the universe.  The history of philosophy is the philosophy of humanity, that great individual, which, with more extended vision than the instruments through which it works, is able to entertain opposing principles, and which, reconciling old contradictions as it discovers new ones, approaches by a necessary and certain growth the knowledge of the one all-embracing truth, which is rich and varied beyond our conception.  In order to energetic labor in the further progress of philosophy, it is necessary to imagine that the