The thought at the foundation of the _Divina Commedia_, nevertheless, is more ancient than Dante, although the details evince marvellous fertility of invention. The idea of a descent to the underworld is the groundwork of a primitive Assyrian epic in comparison with whose antiquity the similar narratives in the Buddhistic and other scriptures are but of yesterday. It is found in Plato’s _Republic_ and the _Odyssey_, both unknown to Dante, who had, however, the sixth book of the _Æneid_ by heart, and implies his obligation by making Virgil his guide. This is a much more likely source for his poem than the vision of Tundal and other similar mediæval legends, which are nevertheless important as showing how strong was the hold of the conception upon the popular mind. The vast difference between Virgil’s treatment and Dante’s needs no elucidation. Virgil writes like a philosopher, and Dante like a prophet. There is, no doubt, abundance of allegory in the _Divina Commedia_, but, generally speaking, the poet’s vision is direct and immediate. Symonds puts the essence of the poem into a word by calling it apocalyptic, and perhaps there is no other great work to which on the whole it presents so close an analogy as the Revelation of St. John; but neither this nor any forerunner affords any precedent for Dante’s astonishing innovation of peopling the unseen worlds mainly with his own and his readers’ contemporaries, men whose hands he had clasped or repelled, with whom he had sat at the council-board or whom he had encountered in conflict, or who, personally unknown, had thrilled him with the report of their fortunes or misfortunes, their good deeds or their crimes. Let any one try to imagine a modern poet treating the nineteenth century in the same manner, and he will be penetrated by a sense of the gigantic nature of the attempt, success in which could only be possible to an intense realist capable of making his phantoms as substantial as when they walked the earth. Yet this is only one side of Dante’s mighty task, which was not only to render the unseen world visible and almost palpable, but to embody what he fondly believed to be a system of infallible dogmatic truth. It need hardly be said that it is to the consummate execution of the former part of his mission that he is chiefly indebted for his fame with the world at large. The _Inferno_, where description and portraiture predominate, has impressed the imagination of mankind far more powerfully than the more mystical and doctrinal _Purgatorio_ and _Paradiso_.