By its very title, 'The Divine comedy' announces its theological purpose. For those not so inclined, the 'Inferno' offered many subsidiary pleasures - compelling narrative drive (both in the adventure of two men descinding into hell, and in the stories of the people they meet); an overpowering visual sense, both in the grand design of Hell's geography and the plan of its punishments, and in the individual details of the sinner's torments; and the endearing characterisation of the heroes, Virgil the stern, noble guide, and Dante, the clumsy, gossipy Everyman.
'Purgatory' has fewer of these delights. Here, it is impossible to avoid the doctrine. Every vast visual set-piece (the Angel fighting off the snake in the Valley of the Princes; the Holy Pageant that stuns the Pilgrim in Eden, complete with griffin-drawn chariot; the masque involving violence to said chariot by eagles, foxes, seven-headed monsters and giants) are all so allegorically pre-determined, each feature a religious symbol, that they lack the dramatic force that would have made their images truly poetic.
The plan of Purgatory - the AntePurgatory where those who left repentance to the last moment must wait; the mountain itself, where seven terraces represent the Deadly Sins to be purged; the crowning Earthly Paradise, or Eden, the gateway to Heaven - bears no real comparison, for the reader, to Hell: one's sympathy naturally inclines towards the eternally damned, and one almost resents the complaints of the saved complaining of their discomforture. The stories told the Pilgrim are also of a lesser order - perhaps proving pure evil to be more (aesthetically) attractive than contrition.
There are some moments when genuine terror intrudes - the visions of violation and tempting lust dreamt by the Pilgrim; the baptism of fire he must pass before entering Eden; the show-trial with Beatrice; while tortuous similes and evocations of nature are framed in poetry of intricate beauty (see Borges remarkable essay on the infinite metaphor in Canto 1).
Mark Musa, like most American annotators, has not heeded the lessons of Charles Kinbote, and his commentary to 'Purgatory' is almost loopily overwritten. He is an amiable, enthusiastic and informative guide, and if his translating choices are sometimes questionable, he has the grace to offer other alternatives. His explanation of the purpose of each image or scene makes it easier to follow the poem with greater understanding (if not necessarily enjoyment). But because he concentrates on every line with such minute detail, he frequently misses the wider design, and so, when he is puzzled by lines that don't fit his view of the Comedy, he has a tendency to blame Dante rather than himself.