perform its systematising task. In its field of labour it will see no goal, but rather the means necessary to reach its goal-the synthesis of knowledge. Investigation of details will no longer be so over-estimated as when science, unconscious of its highest problem, left this to metaphysics. To make science itself philosophy, is the philosophic problem of our day; the highest, most inclusive problem which can ever be proposed in the sphere of knowledge.

PART II.

PROBLEMS OF METAPHYSICS.

CHAPTER I.

REALITY OF THE EXTERNAL WORLD, AND IDEALISTIC

THEORIES.

1. THE meaning of all knowledge rests on the conviction that by it we can discover an order of things already existing.-Given no sun, and no planets, except in the idea of men, the contest for or against the Copernican system would turn upon a comparatively unimportant thing, the more or less simple arrangement of astronomical equations. The heroism of Giordano Bruno, who died for a new theory of the world, must seem to us now but folly, if that idealistic wisdom were correct which denies the existence of planets outside the mind of man. Indeed, what would be left of investigation, if there were no world of things on which consciousness depends in perception, to which experience conforms in all its elements and in the definite relations of its elements-a common world for like knowing beings? The mere agreement of ideas with each other, a play of the mind, could only satisfy a purely subjective interest. Even the agreement of one's own thoughts with the thoughts of other men, by which these get a universal validity, is only possible by a real, not merely imagined bond between thinking subjects; the thought is only communicable when spoken, when it has become sound and word. Realism is the very basis of logic; so much the more is it the basis of positive investigation and science.

There are natural errors to which the mind is exposed, as it is a practical faculty, designed to direct actions.