‘This is the Medzhiner Rebbe,’ explained Spielman, unedifyingly.

‘They call me the Young Rebbe,’ smiled the leader thinly, switching to guttural English. ‘My father, peace upon him, was the Alte Rebbe who never lived to grow old. He died in Treblinka, of typhus, God preserve us, just before the liberation. Towards the end, he gave me the task of keeping the book of souls, where we preserve the names of those who died in the sanctification of God’s name. That is where we shall search for your loved ones, Mr Rapoport.’

Dovidl looked around. The walls were lined with heavy books, but the Rebbe did not reach out for any of them. His source of reference was, like his authority, invisible. He took Dovidl’s hand again, holding it between his own chill palms.

The Alte Rebbe, Spielman explained, had reacted resourcefully to persecution. Powerless to resist by force of arms, he charged his followers to keep a record of every death they saw from the day the Nazis entered their doomed village. The first killings came in his own prayer-house. On the sixth of the ten Days of Penitence, three soldiers shot the Rebbe’s shammes, his beadle, before selecting twelve men who were taken to the forest, ordered to dig a pit and, when it was deemed deep enough, were beaten to death with their own spades. One, Spielman’s elder brother, was kept alive to fill in the grave and spread the terror. He was shot the next day. When the order came for evacuation to Warsaw within the hour, the community was too numbed to flee or resist.

Herded into the ghetto, the Medzhiner Hassidim numbered no more than a hundred families among a hundred thousand, but the Rebbe had given them a mission. Every man, woman and child who died, whether of brutality, starvation or natural causes, every corpse passed on the street, every verified fatality, was to be identified, recorded and written down on lists that were to be sewn into the linings of Medzhiner garments. ‘If we cannot perform our duty of purifying and burying each departed soul,’ ordained the Alte Rebbe, ‘then we must keep its memory alive until a relative can be found to sanctify its memory by saying kaddish. That is our special mitzva.’