Friends, contemporaries, and politicians, as well as admirers, revealed a humble, warm, funny, and open man as tributes flowed in from around the world.
Books of condolence are also to be opened at Belfast City Hall on Monday and the Guildhall, Derry.
Mr Heaney is survived by his wife, Marie, and their children, Christopher, Michael, and Catherine Ann.
A funeral Mass will take place on Monday at the Church of the Sacred Heart in Donnybrook, south Dublin, followed by burial in his birthplace of Bellaghy, Co Derry.
Taoiseach Enda Kenny said it would take Mr Heaney himself to describe the depth of loss Ireland would feel over his death.
“He is mourned — and deeply — wherever poetry and the world of the spirit are cherished andcelebrated,” he said.
The 1995 Nobel prize-winner was born in Apr 1939, the eldest of nine children, on a small farm called Mossbawn near Bellaghy in Co Derry.
The citation for the award praised Mr Heaney “for works of lyrical beauty and ethical depth, which exalt everyday miracles and the living past”.
His publisher, Faber and Faber issued a statement on behalf of the family following his death and went on to describe the poet as a world great and an inspiration for the company. “We cannot adequately express our profound sorrow at the loss of one of the world’s greatest writers,” a spokeswoman said.
“His impact on literary culture is immeasurable. As his publisher we could not have been prouder to publish his poetry over nearly 50 years. He was nothing short of an inspiration to the company, and his friendship over many years is a great loss.”
Mr Heaney was educated at St Columb’s College, Derry, a Catholic boarding school, and later at Queen’s University Belfast, before making his home in Dublin, with periods of teaching in Oxford University and in the US, including at Harvard.
Mr Heaney’s world-renowned poetry first came to public attention in the mid-1960s with his first major collection, Death Of A Naturalist, published in 1966.
The first poem, Digging, resonates with many today who studied it at schools on both sides of the border.
Mr Heaney was never afraid to hide his Irish identity and in 1985, when he wrote An Open Letter in a spat with contemporaries Andrew Motion and Blake Morrison who included his work in The Penguin Book of Contemporary British Poetry.
He objected and used the poem to remove any doubt as to his patriotism. The row sparked the creation of the TS Eliot Prize for a new collection of poetry for anyone from Ireland or Britain, a prize he later won for District and Circle.
He was an honorary fellow at Trinity College Dublin and last year was bestowed with the Seamus Heaney Professorship in Irish Writing at the university, which he described as a great honour.
A year earlier, he donated his manuscripts to the National Library of Ireland, a move which caused consternation in some academic circles in Belfast for overlooking his alma mater Queen’s.
In 1994, a year before he was elevated to the ranks of WB Yeats and Samuel Beckett with the Nobel award, Heaney was asked while teaching in Harvard if his poetry suffered as a result of academia.
“For better or worse — I now feel for worse, earlier on I felt for better — I believed that poetry would come as a grace and would force itself through whenever it needed to come.”
Poet Theo Dorgan said poetry flowed into Mr Heaney and through him, rather than being created.
President Michael D Higgins said his contribution “to the republics of letters, conscience, and humanity was immense”.
“Generations of Irish people will have been familiar with Seamus’s poems. Scholars all over the world will have gained from the depth of the critical essays, and so many rights organisations will want to thank him for all the solidarity he gave to the struggles within the republic of conscience.”
A year after his Nobel win, he was made a Commandeur de L’Ordre des Arts et Lettres by the French ministry of culture.
Belfast Poet Laureate, Dr Sinéad Morrissey, said the “poet-superstar” “seemed peculiarly destined for the kind of living success that is almost unimaginable”.
Ian Martin, a writer of The Thick Of It, said he will toast Heaney and “binge-read” his work.
Andrew Motion, a former British poet laureate, said: “Seamus was a great poet — of Ireland and the world, a brilliantly shrewd and generous writer about poetry, and a person of exceptional grace and intelligence and integrity.
“A wonderful man, in fact: as modest and kindly as he was gifted and principled.”
Mr Heaney was due to deliver a speech at the Linen Hall Library in Belfast next Tuesday and make an address at Amnesty International’s ambassador of conscience award — named after a poem he wrote for the organisation in 1985 — next month.