"You may choose to look the other way but you can never say again that you did not know." -- William Wilberforce, to the English parliament, 1789.
Wilberforce was speaking of slavery in his dogged pursuit of abolition, but more than two centuries later, we are no strangers to looking the other way when it suits us, as it often does.
This week, world leaders are meeting in New York for summits on refugees and migration hosted by UN secretary-general Ban Ki-Moon and US president Barack Obama.
The sheer weight of human displacement should torment our conscience: 65 million people displaced by violence and poverty, including 28 million children; 21 million people turned into refugees, half of them children. Today, nearly one in every 200 children in the world is a refugee.
But the mood is darkly sceptical. Amnesty has already written off the proposed "New York Declaration" as an "abject failure", stripped of substance, while Nobel laureate Malala Yousafzai has described the summit as a "pageant of sympathy" as she called for more funds to educate girls in refugee camps to help them avoid being forced into early marriage or child labor.
President Obama has signalled he will press for specific commitments from governments to relieve the refugee crisis. During the Muslim holiday of Eid al-Adha, he said, in a statement: "We are reminded of the millions of refugees around the globe who are spending this sacred holiday separated from their families, unsure of their future, but still hoping for a brighter tomorrow. And as a nation, we remain committed to welcoming the stranger with empathy and an open heart -- from the refugee who flees war-torn lands to the immigrant who leaves home in search of a better life."
The Obama summit is pay to play. Those who attend -- including Australia -- will be expected to ante up. And, as one of the wealthiest nations on Earth, Australia can and should do more, if only because doing nothing is not an option, as a shocked Europe discovered when hundreds of thousands of refugees suddenly broke from the misery of the Middle East.
Malcolm Turnbull should embrace this summit as an antidote to the poison that has seeped into our national conscience on the issue of refugees and asylum seekers.
Aid agencies, including World Vision, have called for Australia to lift its humanitarian intake from 13,750 to 30,000 by 2018-19; quickly resettle the remainder of the 12,000 Iraqi and Syrian refugees committed to in September 2015; end the indefinite detention of those held on Manus Island and Nauru; and restore the Australian aid budget from the lowest level in our history.
Recently, the historian Alan Atkinson re-wrote a compelling essay about the Australian national conscience, in the Australian Book Review. It is titled: "How do we live with ourselves?"
Atkinson argues that our national conscience has been the quiet, sometimes jarring companion of our national character and easy-going national image, the "whispering in the bottom of our hearts", and that two issues in particular continue to trouble that national conscience: the dispossession of Aboriginal people and the question of refugees.
"Some parts of the refugee question are complicated, just as the rights and wrongs of original British settlement might be said to be complicated, but some parts are simple," he writes. "One morally simple aspect of British settlement was frontier brutality, and one morally simple aspect of Australian refugee policy is the brutality of refugee detention, especially offshore. They are strictly comparable. They both traumatise conscience..."
Australian aid, he says, is "the neatest measure of the national conscience", an index of a nation's moral self-confidence that Wilberforce would have called an index of 'public spirit'.
He describes conditions in Australian refugee camps as a "total collapse of the national conscience" and a "simple dereliction of moral dignity".
I think Atkinson is right and that he is pointing to a deep truth and a perplexing problem in our public culture. Australians of conscience are aghast at our treatment of refugees, and they are variously confused and ashamed at the continuing impact of racism, in both policy and the wider culture. But so feeble is the state of the national conscience that those who raise their voices often seem to be shouting into the wind.
Conscience doesn't always win, and it rarely wins quickly. Most often those who stand up in the public square on matters of conscience face long and lonely battles, even if ultimately vindicated.
But it is nonetheless to be treasured and promoted because it remains one of the major engines of change for good in the world, and in our own country.
There has never been a better time for an earnest and honest national conversation about where our collective conscience is pointing.