those which are given in the second volume, and which correspond to each of the four books that contain the exposition of my own doctrine. In the case of the latter, I have chosen this form of enlarging and improving them, because the five and twenty years that have passed since they were composed have produced so marked a change in my method of exposition and in my style, that it would not have done to combine the content of the second volume with that of the first, as both must have suffered by the fusion. I therefore give both works separately, and in the earlier exposition, even in many places where I would now express myself quite differently, I have changed nothing, because I desired to guard against spoiling the work of my earlier years through the carping criticism of age. What in this regard might need correction will correct itself in the mind of the reader with the help of the second volume. Both volumes have, in the full sense of the word, a supplementary relation to each other, so far as this rests on the fact that one age of human life is, intellectually, the supplement of another. It will therefore be found, not only that each volume contains what the other lacks, but that the merits of the one consist peculiarly in that which is wanting in the other. Thus, if the first half of my work surpasses the second in what can only be supplied by the fire of youth and the energy of first conceptions, the second will surpass the first by the ripeness and complete elaboration of the thought which can only belong to the fruit of the labour of a long life. For when I had the strength originally to grasp the fundamental thought of my system, to follow it at once into its four branches, to return from them to the unity of their origin, and then to explain the whole distinctly, I could not yet be in a position to work out all
