The serving Fianna Fáil TD Brennan died on Wednesday, at the age of 60, after battling cancer for more than a year.
Taoiseach Brian Cowen, Tánaiste Mary Coughlan and the majority of the Cabinet, including Green Party leader John Gormley and former PD leader Mary Harney, were in attendance.
President Mary McAleese, who had attended the removal on Thursday night, was represented by her aide-de-camp at yesterday’s service in the Holy Cross Church, Dundrum.
Also in attendance yesterday were former taoisigh Bertie Ahern and Albert Reynolds,
Fine Gael deputy leader Richard Bruton, Labour leader Eamon Gilmore and a host of other past and present politicians.
The chief mourners were Mr Brennan’s wife Ann, sons Shay and Eanna, daughters Daire, Aoife, Sine and Breffni, two grandchildren, brothers Joe, Eamon and Terry and sister Carol.
In his homily, chief celebrant Fr Enda McDonagh said: “Seamus died before his time but, as the reading from the Book of Wisdom reminds us, we may not measure a man’s value — anybody’s value — by length of years.
“Seamus’s years were filled — filled with love and energy and care and service, to his family and to his country.”
Fr McDonagh said while it was an occasion that brought much pain and grief, it was important to remember the lessons Mr Brennan’s life had offered.
Mr Brennan had always been devoted to his country, and contributed immensely to the “new Ireland”.
Fr McDonagh said it was important to restore that sense of patriotism and duty to Irish life.
“Public service takes a hard beating in the media… but I don’t want to talk about simply politicians or civil servants or whoever, because we are all, as citizens, called to be public servants — servants of the public good of this country.
“Seamus carried that challenge gracefully and courageously. We need to pass it on, we need whole new generations of younger people committed to the service of our country.”
Offertory gifts presented by relatives at the service consisted of a family photograph to symbolise Mr Brennan’s love of family; a Galway jersey, representing his pride in his county of birth; a return ticket for the Luas, in acknowledgement of his close association with that project while transport minister; and a copy of the Constitution, in a bow to his public service.
Hymns included Land of All Hopefulness and How Great Thou Art, while a fiddler played Galway Bay and Dublin in the Rare Old Times.
One of Mr Brennan’s favourite poems, The Village Schoolmaster by Oliver Goldsmith, was read out at the end of the service.
Mr Brennan was buried in St Nahi’s graveyard in Dundrum.