the branches of the system with the fulness, thoroughness, and elaborateness which is only reached by the meditation of many years—meditation which is required to test and illustrate the system by innumerable facts, to support it by the most different kinds of proof, to throw light on it from all sides, and then to place the different points of view boldly in contrast, to separate thoroughly the multifarious materials, and present them in a well-arranged whole. Therefore, although it would, no doubt, have been more agreeable to the reader to have my whole work in one piece, instead of consisting, as it now does, of two halves, which must be combined in using them, he must reflect that this would have demanded that I should accomplish at one period of life what it is only possible to accomplish in two, for I would have had to possess the qualities at one period of life that nature has divided between two quite different ones. Hence the necessity of presenting my work in two halves supplementary to each other may be compared to the necessity in consequence of which a chromatic object-glass, which cannot be made out of one piece, is produced by joining together a convex lens of flint glass and a concave lens of crown glass, the combined effect of which is what was sought. Yet, on the other hand, the reader will find some compensation for the inconvenience of using two volumes at once, in the variety and the relief which is afforded by the handling of the same subject, by the same mind, in the same spirit, but in very different years. However, it is very advisable that those who are not yet acquainted with my philosophy should first of all read the first volume without using the supplementary books, and should make use of these only on a second perusal; otherwise it would be too difficult for them to grasp the
