And do you know, it turned out that every single person working, recruited for the camps, had been through the euthanasia programme. That had been their, sort of, introduction to it. So that the idea of gassing somebody had already been put into their heads as something that could be done. But when he was first sent to help build one of these camps, when he first realised what the purpose of the gasworks was, it was a hideous shock. And he and a friend of his said, 'What are we going to do?' And they daren't do anything, they daren't say they wouldn't, because by that time they were so implicated, they said that it would be the end. And the thing is, it wouldn't probably have been, but they thought it would be. And so they went ahead, still not saying anything to their wives. But his wife was allowed to come and stay with him once. This was not at Treblinka, this was at the camp before, Sobibór. And she found out what was going on and was horrified, absolutely horrified. Couldn't sleep with him, couldn't let him touch her, and went home. And he was shattered, because he adored his wife. But she then… I think it was she who went and talked to a priest about it, and the priest said, 'It's not up to us to judge'. So she began to think, 'Oh well, perhaps it's all right'. And so she softened towards it and she accepted it. And he was able to say to her, 'Look, I have never, myself, killed anybody'. Which, strictly speaking, he hadn't. Even at Treblinka. What he had done was he had brought order to an absolutely ghastly chaotic condition. I mean, the description of what that place was like when he first went into it is unbelievable. And it was a slow process, but he brainwashed himself into being two people, really. Very, very interesting to see how it worked. And there was an extraordinary moment when he'd escaped, got away. Of course, that was an interesting part of the book, too, how he did escape, how those old Catholics all helped them escape. And he was living a perfectly respectable life in the motor factory, German factory, making German cars in Brazil. And he was making a train journey and the train stopped outside a town where there was a big, big slaughterhouse for cattle. And there was cattle beside the train in pens, waiting to go into the slaughterhouse. And he looked at it and the cattle were all there, sort of looking at the train. And he suddenly saw them as being the freight. He called them the freight. It meant the trains that had come in. And he was never again able to eat meat. And she found out from his wife that this was true. He'd come home one day from a journey. He hadn't ever said why, but he'd never eaten meat again from that day. He'd never had dreams, he'd never had nightmares, but he couldn't eat meat since he'd seen the cattle waiting to go in to be slaughtered. Eugh.

And she got him to the point, finally, at the end, where he said, 'Yes, I was guilty. I ought not to be alive'. And it wasn't quite the last time she saw him, or was going to see him, because he wanted… it was the end of their meetings, but he was going to come back after the weekend, because he wanted to look something up. He was a very pedantic man. He'd become very much involved in this business, and he wanted… he had certain facts that he wanted to check and let her know. So she went back… was going to go back to the prison after the weekend, and they rang up and said, 'He's dead'. And they said… she said, 'Did he kill himself'? And they said, 'No, he just died'. He'd said, 'I ought to be dead', and he died. And she'd…The Telegraph had not let her use that in the story, because they said no one's going to believe it. But it was true.

But I don't know that it actually helps to understand about evil, really, but it did show very, very clearly how this sort of thing built in these people. And that if at any point one of them had said, whether it was the wife or the husband, 'No, this is too evil, it can't be done; even if we lose our lives, we're not going to do it'… it would stop.

So it built at tiny increments, that it built. And it made one think, at the end, one has never got to accept things that one knows are wrong. So it's a very valuable… I mean, it didn't just make one think it in theory, it made one think it in the marrow of one's bones.