I am haunted by the story of Moishe the Beadle. Elie Wiesel opens his unbearably painful Holocaust memoir, Night, with the story of this kind and deeply humane man. Moishe the Beadle was the young Wiesel's dedicated teacher. They studied the Torah and Jewish mysticism together night after night, once the Jews of the small Hungarian town of Sighet had left synagogue for home.
One day in the early 1940s, all the foreign Jews of Sighet were expelled from the town. Moishe the Beadle was one of them. He and hundreds of fellow Jews were crammed into cattle-wagons by the Hungarian police, leaving Wiesel and many others in tears on the station platform.
The Jews on this particular train faced the fate of terrible numbers of Holocaust victims. Once across the border into Poland, they were taken to a forest by the Gestapo, forced to dig huge trenches and then shot one by one. In a scene that stays with you like a sick nightmare, it must be recorded that infants were tossed in to the air and used as targets for the Nazi machine guns.
Extraordinarily, Moishe survived the massacre. Shot in the leg and left for dead, he returned as soon as he could to Sighet to warn the Jewish community of the genocidal threat they now faced. No one believed Moishe the Beadle, not even Wiesel. They thought he had gone mad. There was no way these massacres could be happening.
Still Moishe tried, but no one would listen. The young Wiesel asked him why he kept trying and Moishe said: "Life? I no longer care to live. I am alone. But I wanted to come back to warn you. Only no one is listening to me..."
Never has it been so important to remind the world of what can happen when hatred warps minds
Moishe was desperate to bear witness to what he had seen. The importance of testifying to the story of the Holocaust is a central theme of Wiesel's Night, of the work of Primo Levi, of Yad Vashem, of the Holocaust Educational Trust, of the Wiener Library, of survivor testimonies and of crucial courses in schools and universities in Israel, the UK and beyond.
As a Jew growing up in North-West London, the dark, painful shadow of the Holocaust has been part of my life since an early age.
Yet I only began to understand the full scale of its horrors when I studied Nazism at school. By analysing Third Reich primary source documents, reading books by Ian Kershaw and Gitta Sereny and watching documentaries that told survivors' stories, I built my knowledge of the industrial scale of this genocide that took place within living memory.
Years later, I will never forget my wife's aunt's reaction on seeing an old family suitcase: ''Oh my, that was the suitcase my parents kept by the door in case they needed to leave in a hurry.'' Such were the uncertainties of being a Jewish family in Eastern Europe in the first half of the 20th Century.
Today, we witness the murder of Jewish citizens in France and Belgium, the desperate search for refuge of the Yazidis in the face of the ISIS onslaught and the continuing threats to the Christian community in Iraq and elsewhere.
All around us, we continue to feel the dark shadow of genocidal, religious and racial hatred, whether through testimonies from the past or tragedies in the present. Despite the Holocaust, antisemitic attacks continue in Europe – and indeed have increased in the past year.
In recent days, we have mourned the victims of the Paris kosher supermarket atrocity. In Germany, France, Britain and elsewhere, Jewish men and women have been attacked and synagogues and cemeteries desecrated. Here on the streets of London, swastikas have been displayed at anti-Israel rallies. Centuries-old forms of abuse have found new homes on the internet.
Never has it seemed more important to remind the world of what can happen when racial and ethnic hatred warps the minds and souls of people of any nation or creed.
As we approach the 70th Anniversary of the liberation of Auschwitz-Birkenau, we find a particular moment in time to help ensure that the memory of the Holocaust and its victims of all backgrounds are not forgotten. BBC Television will broadcast a special season of programmes to mark this important anniversary.
The season will draw together documentary, drama and educational content and will also include television coverage of the official remembrance event organised by the Holocaust Memorial Day Trust.
The drama The Eichmann Show will tell the story of the televising of the trial of Adolf Eichmann in Jerusalem. The decision to broadcast the trial and provide the pictures to countries around the world brought the full horrors of the Holocaust to a wide global audience - and allowed many survivors to bear witness.
The BBC will also repeat Claude Lanzmann's landmark 9½-hour, documentary series, Shoah, and broadcast new documentaries about survivors and their families to accompany it. Touched By Auschwitz is a new 90-minute documentary by acclaimed film-maker Laurence Rees. It explores the lives of six survivors and the problems, challenges and triumphs they have experienced as a result of their time in the camps.
Further BBC documentaries will widen the range of testimonies. In A Story Of Remembrance, an Auschwitz survivor, a Jewish German childhood escapee and a rabbi share their experience, and in Freddie Knoller's War, a 93-year-old survivor tells his very personal story.
In his new Preface to the 2006 translation of Night, Elie Wiesel re-asserts the importance of bearing witness to the Holocaust. He writes: ''The witness has forced himself to testify. For the youth of today, for the children who will be born tomorrow. He does not want his past to become their future.''
Perhaps Wiesel was thinking about his friend Moishe the Beadle when he wrote this. They are wise, important words. We must all bear witness.
Danny Cohen is the Director of BBC Television