16. I will only offer one more illustration of the relative position of these successive philosophies. Kant compares the change which he introduced into philosophy to the change which Copernicus introduced into astronomical theory. When Copernicus found that nothing could be made of the phenomena of the heavens so long as everything was made to turn round the spectator, he tried whether the matter might not be better explained if he made the spectator turn, and left the stars at rest. So Kant conceives that our experience is regulated by our own faculties, as the phenomena of the heavens are regulated by our own motions. But accepting and carrying out this illustration, we may say that Kant, in explaining the phenomena of the heavens by means of the motions of the earth, has almost forgotten that the planets have their own proper motions, and has given us a system which hardly explains anything besides broadest appearances, such as the annual and daily motions of the sun; and that Fichte appears as if he wished to deduce all the motions of the planets, as well as of the sun, from the conditions of the spectator;--while Schelling goes to the origin of the system, like Descartes, and is not content to show how the bodies move, without also proving that from some assumed original condition, all the movements and relations of the system must necessarily be what they are. It may be that a theory which explains how the planets, with their orbits and accompaniments, have come into being, may offer itself to bold speculators, like those who have framed and produced the nebular hypothesis. But I need not remind my readers either how precarious such a hypothesis is; or, that if it be capable of being considered probable, its proofs must gradually dawn upon us, step by step, age after age: and that a system of doctrine which assumes such a scheme as a certain and fundamental truth, and deduces the whole of astronomy from it, must needs be arbitrary, and liable to the gravest error at every step. Such a precarious and premature philosophy, at best, is that of Schelling and Hegel; especially as applied to those sciences in which, by the past progress of all sure knowledge, we are taught what the real cause and progress of knowledge is: while at the same time we may allow that all these forms of philosophy, since they do recognize the condition and motion of the spectator, as a necessary element in the explanation of the phenomena, are a large advance upon the Ptolemaic scheme--the view of those who appeal to phenomena alone as the source of our knowledge, and say that the sun, the moon, and the planets move as we see them move, and that all further theory is imaginary and fantastical. FOOTNOTES: [Footnote 295: The substance of this and the next chapter was printed as a communication to the Cambridge Phil. Soc. in 1840.] [Footnote 296: Or in the earlier editions, in the _Philosophy of the Inductive Sciences_.] CHAPTER XXV.