When journalist Stan Grant stepped onto the podium in a large Sydney hall on a cold October evening to address a crowd of about 100, he had only an idea of what he wanted to say.

What emerged has gone viral online. Grant has been compared to US civil rights activist Martin Luther King and his speech labelled our greatest against racism.

And, unbelievably, it was delivered off the cuff.

"I didn't want to write anything, I didn't want to be standing there looking down at notes. I just wanted to look people directly in the eye. I wanted to make a statement about how we live with the weight of history."

Not that Stan Grant needed to practise his speech beforehand. Like his maternal grandfather, Keith Cameron, Grant is a natural orator. Growing up, he would listen to his grandfather tell stories about love and survival in the country of their ancestors.

The speech was delivered at the IQ2 Racism Debate on October 27, but released by the Ethics Centre online only last week.

"In the winter of 2015 Australia turned to face itself," Grant said, voice booming through the champagne-sipping crowd. "It looked into its soul and it had to ask this question: Who are we?"

With a description of what happened to footballer Adam Goodes last winter, when booing on the field sounded a "howl of humiliation", the journalist began his powerful speech.

Returning from covering Prime Minister Malcolm Turnbull's visit to Washington for Sky News, Grant says the response to his speech has been overwhelming.

"It's been astounding, really. It took me by surprise, I had returned from Washington as it was being posted and then to see it take on this whole new life, considering I had given the speech some months before, it was really surprising.

"I didn't anticipate that sort of reaction when I first gave the speech It was just something that came very naturally to me, I just wanted to make a statement about how we see Australia and how my family in particular has navigated Australia and dealt with the weight of history here.

"But other people have given these types of speeches before, people who have been fighting these battles well before me so it was really surprising and really humbling that people would come to it but at the same time, really humbling that Australians are wanting to have this hard conversation and wanting to grapple with these issues."

A 'Martin Luther King' moment ...

Journalist Mike Carlton described Grant's speech as a "Martin Luther King moment" on Twitter - a description quickly picked up and used widely by Australian media.

"That's really flattering but I am not in any way worthy of that sort of comparison," Grant said of the juxtaposition. "It's a little bit embarrassing. I'm not even saying that what I have to say or my contribution sits with the contribution of other Indigenous people in Australia who have just blazed a trail."

After the speech went viral, Grant told Fairfax Media that as a journalist he had travelled extensively and saw how dark pasts could cloud the path forward.

"We have struggled with dispossession, we have struggled with colonisation, conflict, we are traumatised by our history in the same way that the people I report on overseas are traumatised by their history," he said.

"And just trying to navigate that as a person, as a human being, as families, as mother and fathers and uncles and cousins and brothers and sisters is extraordinarily difficult and it is tiring for Aboriginal people in Australia. So I just wanted to make a very personal statement about an amazing country but a country that can be better and whose people can command that it do better.

"So to put it in the pantheon of people like Martin Luther King, I wouldn't even mention myself in that breath... I am not anywhere near being considered like a giant like that."

'A pretty news face, a communicator of the highest order'

Author and public speaker Tony Wilson, who curates a website comprised of his favourite speeches, said Grant's words that night were "as good a speech on racism that we have had in Australia".

"Both in terms of delivery and content, it intertwines the personal with the political and it shines a light on that uncomfortable part of our history that we often think of as 'too long ago' or 'not me'.

On his website Speakola, Grant's speech as been "a smash hit" - already viewed by thousands. "Overwhelming the response has been positive, people who want to reflect on this part of our history and think Australia needs to change. A very small minority have reacted angrily.

"What's surprising about Stan Grant is that he has grown from someone who might have just been another talking head, a pretty news face, into a communicator of the highest order.

"He has written a timeless speech, beautifully sculptured, brilliantly delivered. He's not Martin Luther King, no mortal will hit those rhetorical heights, but it's as close as we have come."

When told that Grant improvised that cold evening in October, Wilson is shocked. "That's ridiculous. I honestly can't believe that," he said.

"The structure of it was just so good, he moved from the present day with Adam Goodes stating the contentious truth then took us back to a personal and collective past in such an ordered way that I'd just assumed meticulous preparation."

Living with the weight of history

Grant said he didn't plan what he would say on purpose.

Because it was personal, the words came naturally. "I've lived it, my family have lived it. I was raised on these stories. My people are extraordinary oral storytellers, and this is what we do. I just wanted to make a very direct, a very honest heartfelt statement about how we deal with our history."

In the speech, Grant described the Australian dream as "rooted in racism" and said the past haunts us still, speaking of the lower life expectancy and higher rates of incarceration experienced by indigenous Australians.

He said we sing of the dream in our anthem that doesn't exist. "But my people die young in this country - we die 10 years younger than average Australians - and we are far from free."

He called for Australians to acknowledge history and have a hard conversation about the past.

On the eve of Australia Day, Grant said it was important to be proud but to also hold ourselves to account.

"We can be a country that can grapple with the unresolved grievance that still sits at the heart of settlement. We cannot allow and we cannot accept Indigenous people living in the conditions they have to endure today. It is unacceptable and it is especially unacceptable for a nation that has so much to be proud of."