In his journey to the heart of darkness, Rachel wrote hundreds of pages filled with incredibly technical details about the camps and the appalling, unimaginable stories he heard along the way – some from the guides who showed him round the camps, some from former prisoners who had come to make pilgrimage. Meeting survivors was incredibly painful for him. He wrote pages and pages about it, harrowing and heartbreaking. Sometimes he’d pretend to be a researcher, or a relative of someone who’d been in the camps. He’d persuade them to talk, press them for the most precise, the most intimate details of what they had suffered. He collated the names too, although he already knew all of this, he had researched every detail, he had index cards about everything, though I have to say most of them are illegible. The notes he made from the books he read are filled with formulas and symbols, diagrams and sketches and quotes about how the camp prisoners were fed, how the laundry worked, what medical services existed, about the sectors where the clothes were sorted, the laboratories where the experiments were done, about the workings of the famous selection Kommissionen, about the black market that operated in the camps, about the despicable behaviour of the SS officers, constantly on the lookout for someone with a stash of jewellery, for a pretty girl like Nadia, for a bottle of booze or a nice fur coat or a brawl they could cheer on, he wrote about the military ceremonies, the civil and religious commemorations, the inspections when the Bonzen came round, the brothels for the Kapos, the brothels reserved for the officers. He knew all the books by heart, but he needed to hear it from the mouths of those who had lived in the camps, who forgot that there existed a world outside, a world where people lived and danced and read books, where they learned and loved and bought flowers, raised children and thanked God for His blessings. It was uncomfortable, Rachel says, but he was tactful, asked questions only if he felt someone needed to talk, and would say nothing and stare straight ahead when a man began to choke on his sobs. He’d ask in an offhand way if they remembered their guards – names, ranks, whether they had any particular vices, whether some were more cruel than the rules dictated, whether some behaved humanely. But he always came back to the gas chambers, to the Sonderkommando, the Einsatzgruppen, the soldiers who took the prisoners whose turn it was to take a shower, to that self-effacing man – the chemical engineer who prepared the Zyklon B – and asked if they remembered his name. He felt unspeakably guilty, forever thinking, this man knew my father, he has never forgotten him, he will never forget him, I have to tell him, this is his truth as much as it is mine: Sir, I need to tell you, I am Hans Schiller’s son. I don’t think he ever told anyone – or if he did he doesn’t mention it in his diary. It would have been a terrible thing to do, it would simply have been adding to their suffering.