Schelling expresses himself as follows, concerning the chief principles of a philosophy of nature. Nature is a suspension (_Schweben_) between productivity and product, which is always passing over into definite forms and products, just as it is always productively passing beyond these. This suspension indicates a duality of principles, through which nature is held in a constant activity, and hindered from exhausting itself in its products. A universal duality is thus the principle of every explanation of nature; it is the first principle of a philosophic theory of nature, to end in all nature with polarity and dualism. On the other hand, the final cause of all our contemplation of nature is to know that absolute unity which comprehends the whole, and which suffers only one side of itself to be known in nature. Nature is, as it were, the instrument of this absolute unity, through which it eternally executes and actualizes that which is prefigured in the absolute understanding. The whole absolute is therefore cognizable in nature, though phenomenal nature only exhibits in a succession, and produces in an endless development, that which the true or real nature eternally possesses. Schelling treats of natural philosophy in three sections: (1) the proof that nature, in its original products, is _organic_; (2) the conditions of an _inorganic_ nature; (3) the reciprocal determination of organic and inorganic nature. (1.) _Organic nature_ Schelling thus deduces: Nature absolutely apprehended is nothing other than infinite activity, infinite productivity. If this were unhindered in expressing itself, it would at once, with infinite celerity, produce an absolute product, which would allow no explanation for empirical nature. If this latter may be explained—if there may be finite products, we must consider the productive activity of nature as restrained by an opposite, a retarding activity, which lies in nature itself. Thus arises a series of finite products. But since the absolute productivity of nature tends towards an absolute product, these individual products are only apparent ones, beyond each one of which nature herself advances, in order to satisfy the absoluteness of her inner productivity through an infinite series of individual products. In this eternal producing of finite products, nature shows itself as a living antagonism of two opposite forces, a productive and a retarding tendency. And, indeed, the working of this latter is infinitely manifold; the original productive impulse of nature has not only to combat a simple restraint, but it must struggle with an infinity of reactions, which may be called original qualities. Hence every organic being is the permanent expression for a conflict of reciprocally destroying and limiting actions of nature. And from this, viz., from the original limitation and infinite restraint of the formative impulse of nature, we see the reason why every organization,