The state funeral of Albert Reynolds is continuing in Donnybrook in Dublin, and has heard a moving eulogy from his son Philip.
Mr Reynolds died last Thursday, aged 81, after a long illness.
Figures from the worlds of politics, business, sport and showbiz have gathered to pay tribute to the former Taoiseach.
His remains are being removed to Shanganagh cemetery in Shankhill in south Dublin for burial.
Delivering the eulogy, his son Philip said it was a great tragedy that Mr Reynolds' illness meant the youngest members of his family never got to know him.
He added: "He leaves us with a huge challenge and an amazing opportunity - to raise a family, run a country or rule a world (with) the simple, innate good(ness) that was dad.
"Your work is done here, dad. Rest in peace."
Mr Reynolds' daughter Andrea also delivered a tribute to her father:
Among those attending the funeral were John Major, who signed the Downing Street Declaration with Mr Reynolds in 1993 and paved the way for peace talks involving the Irish and British governments and Sinn Féin.
Martin McGuinness was also attending, along with Liam Cosgrave, the oldest surviving former taoiseach, and Mr Reynolds' successor as Fianna Fáil leader, Bertie Ahern.
A large number of members of the judiciary also attended as did Church of Ireland Archbishop Michael Jackson.
Taoiseach Enda Kenny also attended, along with President Michael D Higgins, a minister in Mr Reynolds' second government.
Figures from politics across Ireland attended including the former SDLP leader and Nobel prize winner John Hume, Sinn Féin president Gerry Adams, Alasdair McDonnell, leader of the SDLP, and Northern Ireland Secretary of State Theresa VIlliers.
Other former taoisigh at the service included Brian Cowen and John Bruton, while former president Mary McAleese also attended.
A large group of figures from Longford County Council also attended, as did Lord Mayor of Dublin Christy Burke.
The Mass was celebrated by Fr Brian D’Arcy, a close family friend, with Archbishop Martin and a number of other concelebrants.
Fr D'Arcy praised Mr Reynolds as a peacemaker with a sincere interest in breaking the cycle of political violence in Northern Ireland long before he came to power.
“His motives were pure,” mourners were told.
Fr D’Arcy revealed that letters from an unnamed source addressed to Mr Reynolds were left at the Passionist monastery where the cleric is based in Enniskillen, Co Fermanagh, in the years before his friend of 50 years became taoiseach.
The priest delivered them personally to the Reynolds home and took other letters in reply back to be left at the monastery.
“Albert thought deeply about violence. He knew peace is more than absence of war but he knew that peace could not take root until the violence stops,” Fr D’Arcy said.
“For him peace was the only battle worth waging. He knew that peace was not achieved only by talking to your friends, you must talk to your enemies and make peace with them.”
Fr D’Arcy added: “He took personal and political risks but all he was doing was giving peace a chance.”
The cleric told mourners that Mr Reynolds should be remembered in the same breath as John Major, Mr Hume and Mr Adams and the late Father Alex Reid, the Redemptorist priest based at Clonard in west Belfast who acted as an intermediary in the peace process.
Fr D’Arcy said the funeral should also remember the 4,000 deaths in the Troubles but also the countless lives Mr Reynolds’s work helped save.
The politician, businessman and deal-maker was also remembered as a dedicated family man.
A photograph on the mass booklet showed him with his wife Kathleen with the quote: “Marrying Kathleen was the best decision of my life.”