Described variously as the greatest poem of the European Middle Ages and, because of the author's evangelical purpose, the `fifth Gospel', the Divine Comedy is central to the culture of the west. The poem is a spiritual autobiography in the form of a journey - the poet travels from the dark circles of the Inferno, up the mountain of Purgatory, where Virgil, his guide leaves him to encounter Beatrice in the Earthly Paradise. Dante conceived the poem as the new epic of Christendom, and he creates a world in which reason and faith have transformed moral and social chaos into order.