Men have tried in various ways to bring the immeasurable greatness of the material universe nearer to the comprehension of us all, and then they have seized the opportunity to make edifying remarks. They have referred perhaps to the relative smallness of the earth, and indeed of man; or, on the contrary, they have pointed out the greatness of the mind of this man who is so insignificant—the mind that can solve, comprehend, and even measure the greatness of the universe, and so forth. Now, all this is very well, but to me, when I consider the vastness of the world, the most important point is this, that the thing-in-itself, whose manifestation is the world—whatever else it may be—cannot have its true self spread out and dispersed after this fashion in boundless space, but that this endless extension belongs only to its manifestation. The thing-in-itself, on the contrary, is present entire and undivided in every object of nature and in every living being. Therefore we lose nothing by standing still beside any single individual thing, and true wisdom is not to be gained by measuring out the boundless world, or, what would be more to the purpose, by actually traversing endless space. It is rather to be attained by the thorough investigation of any individual thing, for thus we seek to arrive at a full knowledge and understanding of its true and peculiar nature. The subject which will therefore be fully considered in the next book, and which has, doubtless, already presented itself to the mind of every student of Plato, is, that these different grades of the objectification of will which are manifested in innumerable individuals, and exist as their unattained types or as the eternal forms of things, not entering themselves into time and space, which are the medium of individual things, but remaining fixed, subject to no change, always being, never becoming, while the particular things arise and pass away, always become and never are,—that these _grades of the objectification of will_ are, I say, simply _Plato’s Ideas_. I make this passing reference to the matter here in order that I may be able in future to use the word _Idea_ in this sense. In my writings, therefore, the word is always to be understood in its true and original meaning given to it by Plato, and has absolutely no reference to those abstract productions of dogmatising scholastic reason, which Kant has inaptly and illegitimately used this word to denote, though Plato had already appropriated and used it most fitly. By Idea, then, I understand every definite and fixed grade of the objectification of will, so far as it is thing-in-itself, and therefore has no multiplicity. These grades are related to individual things as their eternal forms or prototypes. The shortest and most concise statement of this famous Platonic doctrine is given us by Diogenes Laertes (iii. 12): “ὁ Πλατων φησι, εν τῃ φυσει τας ιδεας ἑσταναι, καθαπερ παραδειγματα, τα δ᾽ αλλα ταυταις εοικεναι, τουτων