La divina commedia

Midway this way of life we're bound upon,
I woke to find myself in a dark wood,
Where the right road was wholly lost and gone

...

[Virgil says] But as for thee, I think and deem it well 
Thou take me for thy guide, and pass with me
Through an eternal place and terrible

Where thou shalt hear despairing cries, and see
Long-parted souls that in their torment dire
Howl for the second death perpetually.

Next, thou shalt gaze on those who in the fire 
Are happy, for they look to mount on high,
In God's good time, up to the blissful quire;

To which glad place, a worthier spirit than I 
Must lead thy steps, if thou desire to come,
With whom I'll leave thee then, and say good-bye;

For the Emperor of that high Imperium
Wills not that I, once rebel to Hid crown,
Into that city of His should lead men home.

Everywhere is His realm, but there His throne,
There is His city and exalted sear:
Thrice-blest whom there He chooses for His own!

Then I to him: "Poet, I thee entreat,
For that great God whom thou didst never know,
Lead on, that I may free my wandering feet

From these snares and from worse; and I will go
Along with thee, St Peter's Gate to find,
And those whom thou portray'st as suffering so."

So he moved on; and I moved behind.

Thus begins Dante's glorious Divine Comedy. 

Illustration by Gustave Dore

The translator of my edition, Dorthory L. Sayers, says in her introduction:

We must also be prepared, while we are reading Dante, to accept the Christian and Catholic view of ourselves as responsible rational beings. We must abandon any idea that we are the slaves of chance, or environment, or our subconscious; any vague notion that good and evil are merely relative terms, of that conduct and opinion do not really matter; any comfortable persuasion that, however shiftlessly we muddle through life, it will somehow or other all come right on the night. We must try to believe that man's will is free, that he can consciously exercise choice, and that his choice can be decisive to all eternity. For The Divine Comedy is precisely the drama of the soul's choice. It is not a fairy-story, but a great Christian allegory, deriving its power from the terror and splendour of Christian revelation. Clear, hard thought went to its making: its beauty is of that solid indestructible sort that is built upon a framework of nobly proportioned bones. If we ignore its theological structure, and merely brose about in it for detached purple passages and poetic bits and pieces we will be disappointed, and never see the architectural grandeur of the poem as a whole.

And here's something quite remarkable - an entire encyclical on Dante, by Pope Benedict XV:

Among the many celebrated geniuses of whom the Catholic faith can boast who have left undying fruits in literature and art especially, besides other fields of learning, and to whom civilization and religion are ever in debt, highest stands the name of Dante Alighieri....

Thus, as he based the whole structure of his poem on these sound religious principles, no wonder that we find in it a treasure of Catholic teaching; not only, that is, essence of Christian philosophy and theology, but the compendium of the divine laws which should govern the constitution and administration of States; for Dante Alighieri was not a man to maintain, for the purpose of giving greater glory to country or pleasure to ruler, that the State may neglect justice and right which he knew well to be the main foundation of civil nations....

And you, beloved children, whose lot it is to promote learning under the magisterium of the Church, continue as you are doing to love and tend the noble poet whom We do not hesitate to call the most eloquent singer of the Christian idea. The more profit you draw from study of him the higher will be your culture, irradiated by the splendours of truth, and the stronger and more spontaneous your devotion to the Catholic Faith.

Dante Alighieri, il Sommo Poeta (the Supreme Poet)

May/June c.1265 – September 14, 1321