Had Dante written only his prose treatises and his minor poems, he would still have come down to us as the most commanding literary figure of the Middle Ages, the first modern with a true literary sense, the writer of love verses whose imagination was at once more delicate and more profound than that of any among the long train of his successors, save Shakespeare alone, and more free from sensual stain than that of Shakespeare; the poet of sweetest strain and fullest control of the resources of his art, the scholar of largest acquisition and of completest mastery over his acquisitions, and the moralist with higher ideals of conduct and more enlightened conceptions of duty than any other of the period to which he belonged. All this he would have been, and this would have secured for him a place among the immortals. But all this has but a comparatively small part in raising him to the station which he actually occupies, and in giving to him the influence which he still exerts. It was in the 'Divine Comedy' that his genius found its full expression, and it is to this supreme poem that all his other work serves as substructure.
The general scheme of this poem seems to have been early formed by him; and its actual composition was the main occupation of his years of exile, and must have been its main, one might say its sufficient, consolation. Never was a book of wider scope devised by man; and never was one more elaborate in detail, more varied in substance, or more complete in execution. It is unique in the consistency of its form with its spirit. It possesses such organic unity and proportion as to resemble a work of the creative spirit of Nature herself.
The motive which inspired Dante in the 'Divine Comedy' had its source in his sense of the wretchedness of man in this mortal life, owing to the false direction of his desires, through his ignorance and his misuse of his free will, the chief gift of God to him. The only means of rescue from this wretchedness was the exercise by man of his reason, enlightened by the divine grace, in the guidance of his life. To convince man of this truth, to bring home to him the conviction of the eternal consequences of his conduct in this world, to show him the path of salvation, was Dante's aim. As poet he had received a Divine commission to perform this work. To him the ten talents had been given, and it was for him to put them to the use for which they had been bestowed. It was a consecrated task to which both heaven and earth set their hand, and a loftier task was never undertaken. It was to be accomplished by expounding the design of God in the creation, by setting forth the material and moral order of the universe and the share of man in that order, and his consequent duty and destiny. This was not to be done in the form of abstract propositions addressed to the understanding, but in a poetic narrative which should appeal to the heart and arouse the imagination; a narrative in which human life should be portrayed as an unbroken spiritual existence, prefiguring in its mortal aspects and experience its immortal destiny. The poem was not to be a mere criticism of life, but a solution of its mystery, an explanation of its meaning, and a guide of its course.