It has already been remarked that the greater part of the punishments of the Inferno are symbolical of the crimes for which they are inflicted, but many of them are so in a far more general relation. Of this kind is, in particular, the representation of a metamorphosis, in which two natures are mutually interchanged and their substance transmuted. No metamorphosis of Antiquity can compare with this for invention, and if a naturalist or a didactic poet were able to sketch with such power, emblems of the eternal metamorphoses of nature, he might congratulate himself upon it. As we have already remarked, the Inferno is not only distinguished from the other parts by the external form of its representation, but also by the circumstance that it is peculiarly the realm of forms and consequently the plastic part of the Poem. The Purgatorio must be recognized as the picturesque part. Not only are the penances here imposed upon sinners at times pictorially treated even to brightness of coloring; but the journey up the holy mountain of Purgatory presents in detail a rapid succession of shifting landscapes, scenes and manifold play of light; until upon its outermost boundary, when the Poet has reached the waters of Lethe, the highest pomp of Painting and Color displays itself;—in the picturing of the divine primeval forest of this region, of the celestial clearness of the water, overcast with its eternal shadow, of the maiden whom he meets upon its banks and the descent of Beatrice in a cloud of flowers, beneath a white veil, crowned with olive, wrapped in a green mantle, and “vested in colors of the living flame.” The Poet has urged his way to light through the very heart of the earth: in the darkness of the lower world forms alone could be distinguished: in Purgatory light is kindled, but still in connection with earthly matter and becomes color. In Paradise there remains nothing but the pure music of the light; reflection ceases, and the Poet rises gradually to behold the colorless pure essence of Deity itself. The astronomical system which the age of the poet invested with a mythological value; the nature of the stars and of the measure of their motion, are the ground upon which his inventions, in this part of the poem, rest. And if he in this sphere of the unconditioned, still suffers degrees and differences to exist, he again removes them by the glorious word which he puts into the mouth of one of the sister-souls whom he meets in the moon, that “every _Where_ in heaven is Paradise.”