There it was, nestled among the secondhand classics, the soft-core pornography and the old National Geographics spread out for sale on blankets and tables along Manhattan’s Upper Broadway. The subtitle on the bedraggled bookjacket announced « A Christmas Oratorio, » a phrase that makes many people think of orchestras and choirs performing Bach or Handel at Carnegie Hall rather than a thin volume of poetry.

But for a small band of faithful readers the long poem in that volume, W. H. Auden’s « For the Time Being, » remains one of the most powerful expressions of the meaning of Christmas in the 20th century.

With its metaphysical musings and theological underpinnings, the poem will never replace « The Night Before Christmas » or the seasonal pageant at Radio City Music Hall. But Auden’s is a Christmas that can glimpse redemption even in the trivialization of Christmas, in the frantic shopping, distracted gaiety and unsuccessful attempts, as he says, to love all of our relatives. This is a Christmas for the day after Christmas. This is a Christmas for grown-ups.

Coming across a tattered copy of his work on a sidewalk might have struck the poet himself as especially suited to the subject of divinity born in a cattle stall.

Someone once said of the perpetually disheveled Auden, « Everything he touched turned to cigarette ashes. » The opposite was also true. He had a touch for turning cigarette ashes to poetry, for transforming everyday idioms, simple meters and rollicking jingles into profound and haunting stanzas. His verses undercut grandiloquence with the mundane and the conversational. In « For the Time Being » he brought this gift to the Christmas theme of the Incarnation, God’s taking on the humblest of forms, power and vulnerability fused, the sacredness of the mundane.

The poem was written in oratorio form as a long dramatic musical composition with a chorus, a narrator and all the characters of the Christmas story. Auden had hoped that his friend Benjamin Britten would set it to music — a task that the distinguished English composer passed by when faced with a text he considered too long. Another composer eventually set an abridged version to music, but, usually, the oratorio is simply read aloud.

As Auden described it, the world that Jesus’s birth silently, but decisively, disrupted was one of sophisticated knowledge undermined by philosophical confusion, of political power sapped by moral complacency. « The evil and armed draw near, » recites the chorus. « The weather smells of their hate/And the houses smell of our fear.  »

It could be the world of 1990. And it was obviously the world of 1941-42 when, not long after his mother’s death and under the shadow of war and personal crisis, Auden wrote the oratorio. The Christianity to which he had recently returned, after sampling the progressive ideologies of the age, was being tested. Whatever joy Christ’s coming may ultimately promise, the poem makes clear that faith, like love, will not be easy.

Love of every sort, erotic and sacrificial, faithful and unfaithful, marital and parental, is evoked here, as it is throughout Auden’s poetry. In a comic turn gleaned from medieval religious drama, a doubting Joseph begs for certainty about Mary’s miraculous pregnancy: « All I ask is one/Important and elegant proof/That what my love had done/Was really at your will. » The Angel Gabriel replies abruptly: « No, you must believe;/Be silent, and sit still. »

Auden’s Joseph, it seems, must atone for all the sins of male arrogance and infidelity. Auden’s Mary, in a lullaby over the manger, laments that through the humanity she has bestowed, God’s own son has become subject to fear, anxiety, tears, solitude and death. Auden’s Magi confront the limits of their analytical reasoning. Auden’s shepherds seek relief from lives of drudgery.

Auden’s Herod is not the raging tyrant that the poet might have drawn from medieval models or the example of Hitler. Instead he is the dutiful public manager, the skeptical apostle of rationality and progress.

« Yes, in 20 years I have managed to do a little, » he tells himself in a long prose passage. « Soft drinks and sandwiches may be had in the inns at reasonable prices » and « the truck-drivers no longer carry guns. Things are beginning to take shape. »

But « this little civilized patch » of empire is still threatened by a howling wilderness of barbaric superstition, he muses. A single spark might ruin everything, and now « judging by the trio who came to see me this morning with an ecstatic grin on their scholarly faces, the job has been done, » he says of the Magi.  » ‘God has been born,’ they cried. »

In no time at all, Herod fears, reason will be replaced by revelation and justice by pity. Society will honor « hermits, bums and permanent invalids » instead of generals, philosophers and statesmen.

« Civilization must be saved even if this means sending for the miltary, » he concludes petulantly. « Why can’t people be sensible? I don’t want to be horrid. »

The oratorio culminates in the narrator’s final words. Christmas has passed and: « Now we must dismantle the tree,/Putting the decorations back into their cardboard boxes. » Now we eat the leftovers and return to « the moderate Aristotelian city/Of darning and the Eight-Fifteen. »

« To those who have seen/ The Child, however dimly, however incredulously, » Auden writes, « The Time Being is, in a sense, the most trying time of all. » The moment of completeness is past, and we are tempted to seek a renewal of intensity even in « some great suffering. » Suffering will come in due course, Auden warns, but the challenge now is to recognize the miracle of God’s entry into all that is routine and mundane. « In the meantime, » Auden concludes: There are bills to be paid, machines to keep in repair, Irregular verbs to learn, the Time Being to redeem From insignificance.