Human Chain is about inheritance  in the fullest sense of the word. If it were a poet such as Philip Larkin writing, human chain would mean "man hands on misery to man". But what makes Seamus Heaney's writing so fortifying is, partly, his temperament: his human chain is tolerant, durable, compassionate and every link is reinforced by literature. In more than one poem he makes this plain, recalling the moment in his younger life (in "Route 110") in an Irish bookshop when a woman in brown overalls with a "marsupial" pocket (a perfect, unexpected adjective) sold him a "used copy of Aeneid VI" in a "deckle-edged brown paper bag". What follows is a poem in which the Aeneid co-exists with autobiography. Heaney reminds you that this is what literature is: another life.

This beautiful and affecting collection includes Heaney's own not-so-distant brush with death. "Chanson d'Aventure" describes a Sunday afternoon ambulance ride (during which, he reflects, he might have quoted Donne, but was not fit to quote anything). This is followed by "Miracle" which is, on the face of it, a religious salutation to miracle workers, "the ones who have known him all along/ And carry him in". But it also indirectly celebrates the workaday help of everyone good enough to help with a recovery  the human chain.

The prevailing tone is retrospective, clear and unflustered  as if written from the vantage point of a small hilltop. The poems are filled with assorted bygones: antique fountain pens, piles of coal, ancient boilers (the better to conjure old flames). The wardrobe is of tweed, linen and calico and tends to the sere. Many poems are tender and welcoming but Heaney was never one for false consolation.

There are bracing elegies here too. "The door was open and the house was dark", in memory of David Hammond, is especially arresting because it refuses the dead man even the briefest afterlife in poetry. Instead, Heaney explores the silence after a death. It is a wonderful idea that silence should develop a life of its own, journeying through the second stanza and retiring into the street. The strangeness rings emotionally true, a reaction to a new relationship with silence. And the last line is an extraordinary release: "On an overgrown airfield in late summer."

Heaney looks steadily at emptiness elsewhere too. In his superb poem, "The Butts", he considers a dead man's suits (his father's?) that hang "slightly bandy sleeved" and "a bit stand-offish" and swing like "waterweed disturbed". And at the end he pulls off  a typical Heaney success  a complete shift of direction. The owner of the suits is alive again and in need of nursing:

And we must learn to reach well in beneath

Each meagre armpit

To lift and sponge him.

So many of these poems are labours of love.

Heaney is conversational and welcoming, often present in his writing as a relaxed host. He never overdresses his poems. "A Herbal", an adaptation of the Breton poet Guillevic, is an example of this restraint  a devotional piece about graveyard plants with secretive bracken and independent grass:

Not that the grass itself

Ever rests in peace.

It too takes issue,

Now sets its face

To the wind

Now turns its back.

It is a last line that echoes another favourite poem from this masterly collection in which the turning of a back brings tears to the eyes. In "The Baler", Heaney remembers Derek Hills who preferred not to face the sunset:

 asking please to be put

With his back to the window.

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In the early 1990s Seamus Heaney began to contemplate how to deal with time passing and the death of family and friends. In a lecture, he contrasted Philip Larkin's poem "Aubade", in which death comes as something dark and absolute and life seems a trembling, fearful preparation for extinction, with Yeats's "The Cold Heaven", which allowed a rich dialogue between the ideas of life as a cornucopia and life as an empty shell. Heaney saw poetry itself, no matter what its content or tone, standing against the dull thought of life as a great emptiness. "When a poem rhymes," Heaney wrote, "when a form generates itself, when a metre provokes consciousness into new postures, it is already on the side of life. When a rhyme surprises and extends the fixed relations between words, that in itself protests against necessity. When language does more than enough, as it does in all achieved poetry, it opts for the condition of overlife, and rebels at limit."

In his 1991 collection Seeing Things he included a poem, "Fosterling", which seemed like a blueprint for how he himself might proceed, speaking of a "heaviness of being" producing "poetry / Sluggish in the doldrums of what happens". And then writing of a change which had come: "Me waiting until I was nearly fifty / To credit marvels. Like the tree-clock of tin cans / The tinkers made. So long for air to brighten, / Time to be dazzled and the heart to lighten."

The blueprint, however, has turned out not to open the way for an easy lightness, or a tone of bright hope, in Heaney's work, but for a struggle that his poems would enact and dramatise between the facts as Larkin presents them in "Aubade" and the idea, which Heaney proposes in his essay, that "the vision of reality which poetry offers should be transformative, more than just a printout of the given circumstances of its time and place".

While his essay clearly comes down on one side, as does "Fosterling", the poems themselves have been more hushed in the presence of mortality, more open to the idea of loss as something pure. His poems have offered consolation or transformation only because they contain tones and phrases that are perfectly tuned; they are true to memory and loss, and thus somehow, at times miraculously, they offer a vision of what is beyond them or above them.

In Human Chain, his best single volume for many years, and one that contains some of the best poems he has written, Heaney allows this struggle between the lacrimae rerum and the consolations of poetry to have a force which is satisfying because its result is so tentative and uncertain. Memory here can be filled with tones of regret and even undertones of anguish, but it also can appear with a sense of hard-won wonder. There is an active urge to capture the living breath of things, but he also allows sorrow into his poems.

He uses a poetic line which sometimes seems complete and whole in its rhythm, and at others is stopped short, held, left hanging. It is as though to allow the rhythm its full completion would be untrue to the shape of the experience that gave rise to the poem, untrue to the terms of the struggle between the pure possibility that language itself can offer and a knowledge of the sad fixtures which the grim business of loss can provide.

The verse structure Heaney seems most at home with here is the one most used in Seeing Things: it contains four stanzas of three lines per stanza, a sonnet without the couplet. This system offers a sort of looseness, a buoyancy, a refusal to close and conclude; it means that the endings of these poems can have a particular pathos, a holding of the breath, "gleaning the unsaid off the palpable", as Heaney has it in his poem "The Harvest Bow".

At times, despite his effort to be consoled, it is as though whatever is being remembered has taken all his heart for speech. This is most apparent in an elegy for the Irish singer David Hammond, which contains four of these three-line stanzas plus one extra line. It is the poem where the struggle between pure lament and the search for comfort in images seems most intense:

The door was open and the house was dark
Wherefore I called his name, although I knew
The answer this time would be silence

That kept me standing listening while it grew
Backwards and down and out into the street
Where as I'd entered (I remember now)

The streetlamps too were out.

If there is a presiding spirit haunting this book, it is Virgil's Aeneid. In Stepping Stones, his book of interviews with Dennis O'Driscoll, Heaney mentions that "there's one Virgilian journey that has indeed been a constant presence, and that is Aeneas's venture into the underworld. The motifs in Book VI have been in my head for years  the golden bough, Charon's barge, the quest to meet the shade of the father."

Human Chain is a book of shades and memories, of things whispered, of journeys into the underworld, of elegies and translations, of echoes and silences. It conjures up the ghosts of three painters  Colin Middleton, Nancy Wynne-Jones, Derek Hill  who spent their lives working with Irish light and Irish weather. The three-part poem "Chanson d'Aventure", describing a journey by ambulance after suffering a stroke, invokes with gentle reverence John Keats, who wrote in a late poem of "This living hand, now warm and capable / of earnest grasping". Heaney describes:

my once capable

Warm hand, hand that I could not feel you lift
And lag in yours throughout that journey
When it lay flop-heavy as a bellpull

The most ambitious poem in the book is an ingenious and moving encounter with Book VI of the Aeneid, with a description of finding a used copy of the book in Belfast and taking it on Route 110 across Northern Ireland ("Cookstown via Toome and Magharafelt"). Slowly the poem moves into the underworld ("It was the age of ghosts"), where it meets, among others, Louis O'Neill, one of the murdered dead in the Troubles, who is the subject of Heaney's earlier poem "Casualty" and wanders in a world of shady memory to emerge in a final poem about the birth of a first grandchild.

Sometimes, it seems, it is enough for Heaney that he remembers. Throughout his career there have been poems of simple evocation and description. His refusal to sum up or offer meaning is part of his tact, but his skill at playing with rhythm, pushing phrases and images as hard as they will go, offers the poems an undertone, a gravity, a space between the words that allows them to soar or shiver.

There is one poem, "Uncoupled"  a diptych in memory of his parents  that has all the placid beauty of a Dutch painting or a Schubert song. Both parts of the poem are structured in the customary four three-line stanzas, both beginning with the same three words "Who is this", both offering a single ghostly image from memory, something hovering between what is lost and what has now been found.

The first part describes his mother carrying a tray of ashes from the house to the ash-pit; it offers a picture of immense, distant dignity, allowing the ashes to be "whitish dust and flakes still sparkling hot", purely themselves, but with all the resonance that they can command besides. The second part is a picture of his father "not much higher than the cattle / Working his way towards me through the pen, / His ashplant in one hand". The father is thus captured in an ordinary moment, but he is "Waving and calling something I cannot hear" because of

all the lowing and roaring, lorries revving
At the far end of the yard, the dealers

Shouting among themselves

but also, it is implied, because time has passed and death has intervened. In the last two lines  the last 20 words of the poem have each only one stark syllable  you watch Heaney struggling between the world of painful fact and something in his own imaginative spirit which insists that language used with sombre tact and care "opts for the condition of overlife and rebels at limit":

So that his eyes leave mine and I know
The pain of loss before I know the term.

Colm Tóibín's Brooklyn is published by Penguin.