In our day demands for a Philosophy of history are rare and received with scant favour; but it seems that those for a Philosophy of nature are again acquiring vigour. On seeking the inward meaning of this fact, it is seen that on the one hand many of those who demand a Philosophy of nature are empiricists, desirous of a natural science elaborated into a philosophy, and therefore not properly of a Philosophy of nature, but of a view of the natural sciences that may supplant philosophy. Other upholders of a Philosophy of nature echo the only programme of such a philosophy, as it was formulated especially by Schelling and by Hegel, but declare themselves altogether dissatisfied with the attempts to carry it out made by Schelling, by Hegel and by the followers of both. They are dissatisfied, but incapable of setting their dissatisfaction at rest by a new attempt at carrying out the programme. They are also without the intellectual courage necessary to question and to re--examine the solidity of the programme itself, which is in their judgment plausible and guaranteed by such great names. For what indeed is more plausible upon first inspection than the affirmation that the empirical sciences must be elevated to the rank of philosophy? It seems that too much mental liberty is needed to understand and to distinguish from the preceding, the somewhat different proposition that empiricism (empirical philosophy) must certainly be elevated to the rank of non-empirical philosophy, but that the _empirical sciences_ must be left in peace to their own methods, without any attempt to render perfect by means of extrinsic additions that which has in itself all the perfection of which it is capable. It seems that more intelligence than is usually met with is necessary in order to recognize that this last proposition does not establish a _dualism_ of spirit and nature, of philosophy and the natural sciences, but for ever destroys every dualism by making of the natural sciences a merely practical formation of the spirit, which has no voice in the assembly of the philosophical sciences, as the object which it has created has no reality. An ultimate tendency can be discerned in the complex movement of the day toward a Philosophy of nature. This is the attainment of the consciousness that reality is on this side of the classifications of the natural sciences, and that the natural sciences must be retranslated into _history,_ by means of a historical consideration (concrete and not abstract) of the facts that are called natural. But this tendency is not something that will attain its end in a near or in a distant future. It has always shown its value and shows it also to-day; it can be recommended and promoted, but neither more nor less than every other legitimate form of spiritual activity can be recommended and promoted. Classifications are classifications; and what man really seeks out, what continually enriches the empirical