Political figures from across Ireland paid their respects at Sacred Heart Church in Donnybrook on Monday, where Mr Reynolds was praised as a peacemaker with a sincere interest in breaking the cycle of political violence in Northern Ireland long before he came to power.
John Hume, Gerry Adams and Martin McGuinness were among the hundreds of politicians, business figures and dignitaries attending the state funeral.
Also there was Sir John Major, who signed the Downing Street Declaration with Mr Reynolds in 1993 and paved the way for peace talks involving the British and Irish governments and Sinn Fein.
Mr Reynolds died last Thursday aged 81 after a long illness.
Requiem mass was celebrated by Fr Brian D'Arcy, a close family friend, who said "His motives were pure."
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."
He said the funeral should also remember the 4,000 deaths in the Northern Ireland Troubles but also the countless lives Mr Reynolds' work helped save.
Northern Irish political figures in attendance also included Alasdair McDonnell, leader of the nationalist SDLP, and Northern Ireland Secretary of State Theresa Villiers.
The mass began with a special mention for Sir John Major's attendance, which was greeted with a round of applause throughout the packed church.
Fr D'Arcy said it was particularly important for the family that the former PM was able to attend.
The chief celebrant told mourners: "His (Sir John's ) words were typical: 'where else would I be on this day?"'
Liam Cosgrave, the oldest surviving former taoiseach, attended along with Mr Reynolds' successor as Fianna Fail leader Bertie Ahern and other former taoisigh Brian Cowen, John Bruton and the incumbent Enda Kenny.
President Michael D Higgins, a minister in Mr Reynolds's second government, was there, along with former president Mary McAleese
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."
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