researches into physical science had been separated into numberless different powers. “It is a needless trouble which many have given themselves, to show how very different is the working of fire and electricity, for every one knows this who has ever seen or heard of the two. But our mind strives after unity in the system of its knowledge; it will not endure that there should be pressed upon it a separate principle for every single phenomenon, and it will only believe that it sees nature where it can discover the greatest simplicity of laws in the greatest multiplicity of phenomena, and the highest frugality of means in the highest prodigality of effects. Therefore, every thought, even that which is now rough and crude, merits attention so soon as it tends towards the simplifying of principles, and if it serves no other end, it at least strengthens the impulse to investigate and trace out the hidden process of nature.” The special tendency of the scientific investigation of nature which prevailed at that time, was to make a duality of forces the predominant element in the life of nature. In mechanics, the Kantian theory of the opposition of attraction and repulsion was adopted; in chemistry, by apprehending electricity as positive and negative, its phenomenon was brought near that of magnetism; in physiology there was the opposition of irritability and sensibility, &c. In opposition to these dualities, Schelling now insisted upon the unity of every thing opposite, the unity of all dualities, and this not simply as an abstract unity, but as a concrete identity, as the harmonious co-working of the heterogeneous. The world is the actual unity of a positive and a negative principle, “and these two conflicting forces taken together, or represented in their conflict, lead to the idea of an organizing principle which makes of the world a system, in other words, to the idea of a world-soul.” In his above-cited essay on “_the world-soul_,” Schelling took the great step forward of apprehending nature as entirely autonomic. In the world-soul nature has a peculiar principle which dwells within it, and works according to conception. In this way the objective world was recognized as the independent life of nature in a manner which the logical idealism of Fichte would not permit. Schelling proceeded still farther in this direction, and distinguished definitely, as the two sides of philosophy, the philosophy of nature and a transcendental philosophy. By placing a philosophy of nature by the side of idealism, Schelling passed decidedly beyond the standpoint of science, and we thus enter a second stadium of his philosophizing, though his method still remained that of Fichte, and he continued to believe that he was speculating in the spirit of the _Theory of Science_. II. SECOND PERIOD. STANDPOINT OF THE DISTINGUISHING BETWEEN THE PHILOSOPHY OF NATURE AND OF MIND.