Prime Minister Kevin Rudd spoke of heroes and humanity, Victorian Premier John Brumby of rebuilding and Governor-General Quentin Bryce of keeping alive the memory of those who perished in Victoria's bushfires.
On a day when sorrow, grief and hope were the themes for memorial services around the country, Mr Rudd told those who had suffered in the fires they were not alone.
At the central service in Melbourne, the prime minister also announced that every year on February 7, the day the fires struck Victoria, Australian flags would fly at half mast.
"In recent days, we have witnessed unspeakable suffering," Mr Rudd said.
"We have lost mothers and fathers, grandmothers and grandfathers.
"We have lost brothers and sisters, sons and daughters, the tiniest of children, family and friends and neighbours.
"All these are precious lives.
"No words can provide solace for grief so personal.
"But simply know this. You who suffer are not alone.
"This great Australian family here assembled and across the nation today is with you."
Around 7,000 people came to the Rod Laver Arena in Melbourne for Sunday's National Day of Mourning service while thousands more gathered around Australia to honour, mourn and reflect.
Mr Brumby told them the fires that took "too many and too much" had also united Australians in grief and revealed human nature at its best.
"They have united us in our response and they unite us all in the task of rebuilding," Mr Brumby said.
"We will rebuild.
"As we join together at this place and across Australia, we open our hearts and offer our prayers to those who have lost so much.
"Our state, our nation, shares your grief and stands with you as one."
Mr Brumby used the service to again thank firefighters and other emergency service workers and volunteers, many of whom were in the audience.
"In these, the very worst of times, we have also seen the very best of human nature," he said.
"So, today, we recognise and thank our heroic firefighters and emergency service workers ... for their courage, their sacrifice, their skill - and for giving so much.
"We thank the millions of Australians - from every state and from every territory - for their extraordinary generosity and support."
Perhaps the most touching address was delivered by Governor-General Quentin Bryce who consoled those who had suffered loss, encouraging them to grieve and to remember.
"In the last two weeks, we have experienced ... devastating ruin, bereavement and pain," Ms Bryce said.
"For the months and years and decades hence, those struck down will re-assemble what has been dismantled of your lives, your property and communities.
"We must allow the thoughts and images and words that have so recently scorched and swamped us to gently settle and find their proper and worthy place in our hearts and minds.
"We must recognise these memories as an inseparable part of us."
Among those for whom it was hoped the service would help most, the gesture was welcomed as an important part of the healing process.
Grandmother Jenny Buxton lost friends, her home and everything she owned.
"I keep thinking of the things I have lost but I am trying to find the positives," Ms Buxton told AAP.
"I wanted to be part of today, the support of everyone has been great and I am grateful for all that we have been given."
Vicki Ruhr from Kinglake came to the service with some friends, but said many others from the devastated area felt it was too early to leave their home community.
"It's all gone so fast the whole thing, a lot of Kinglake people chose not to come today because they just felt they couldn't leave, they wanted to stay on the mountain," she said.
"It's important to know the support is there from our country, we're not just sitting in a little pocket, awareness is there now that we need ongoing support ... sustaining support."
Her friend, Michael O'Meara, said he had lost many friends but Mr Rudd's commitment to rebuild the town was "quite comforting".
"It's a long-term commitment and, as he said, a lot of governments would just forget about what happened, but he made the opposite commitments. I think that's very important," he said.
While the memorial service was underway in Melbourne, other nearby communities prepared for another day of potential disaster on Monday.
Authorities have predicted severe fire weather for Monday and people in the Warburton/Yarra Valley area and near Enoch Point north of the city, warning residents to be prepared to flee.
Country Fire Authority (CFA) State Duty Officer Neil Bumpstead said residents should consider leaving the area on Sunday evening or Monday morning.
At least 209 people are known to have died in the Victorian bushfires, which have been raging since Black Saturday on February 7.