The Holocaust Memorial Day, which is being marked today in many cities including Belfast, is a reminder of the appalling price of sustained hatred and sectarianism.
Six million Jews and millions of others died in that appalling mass murder by Nazi Germany, and the shadows still hang over us.
This is so much more depressing and challenging, given the rise of anti-Semitism today and the inability of one of the major political parties in the United Kingdom to deal properly with such a scourge within its ranks.
The events of the Holocaust are still relatively recent, within the long sweep of history, and we are reminded today of the importance of remembering the awfulness of what happened in the Hitler years.
Members of the wider family of Dr Katy Radford died in the death camps, and in a challenging article in today's paper she reminds us of the importance of understanding how people become contaminated by the toxicity that leads to genocide.
She underlines how the Holocaust did not start with gas chambers but "with whispers and looks".
She warns that it "crept like a virus through communities for whom acceptable levels of segregation, violence and division became intertwined with a perverse sense of national identity, revisionism and a denial of the rights of those wishing to express themselves through diverse rituals and customs".
That hits uncomfortably close to home, and we too have the dark experience of so many who died and were injured in the bitterness of our Troubles, and indeed beyond that.
While our victims are numerically small compared to the vast suffering from the Holocaust, the sense of loss in our midst has been all too real.
Each death is cataclysmic for the family involved.
The hurt lingers on, and we have found it so extremely difficult to deal with heritage issues in Northern Ireland.
Remembering is vitally important, and Dr Radford underlines the need for all of us to "take a long, hard look at how, where and what we commemorate, and why we choose to do it in the way we do".
If we are to learn anything from the past - and we must do so - then it must be about the senselessness of so much suffering, the cruelty which we are capable of, and the lives that are lost.
These are more than enough reasons for remembering.