LAURENCE REES: Let's talk a about the question of race. How central can we say the idea of race was to Nazism?

NORBERT FREI: Well, there are books which simply put it in terms of the 'racial state' and it was important for Hitler and for a couple of important figures. It became increasingly convincing certainly to quite a lot of the ordinary Germans. But I wouldn’t say that it was important right from the start, and I wouldn’t say that all Germans were convinced about it in the mid-1930s. But, on the other hand, you see how nice it is to perceive yourself as the Herrenrasse. There are a couple of nice benefits with perceiving yourself as part of the superior race even during the war, and you get adjusted to the idea. Despite the fact that it’s a deeply anti-Christian idea and, after all, Germany was a Christian country, it’s an idea which you can work with, get accustomed to, and take the best out of it for yourself. And this is certainly what also happened.

LAURENCE REES: And the other fascinating aspect to it is that so many very intelligent people were involved in this.

NORBERT FREI: Oh, yes, these were educated people, at least the managers of the extermination.

LAURENCE REES: But we normally value education as a protection against this kind of thing?

NORBERT FREI: Yes, well obviously this is too easy a way of seeing it. Of course the actual killing was done by mostly ordinary men, ordinary soldiers, ordinary Waffen SS, but behind the desks there were indeed educated people, and they kind of explained themselves into this project I would say. They made themselves understand what they were doing. They were probably reflecting on it, some of them, someone like Ohlendorf. And they knew at a certain point that they even had to take part in the actual killing because this is what the code of their community would ask for. I mean, they wouldn’t always sit behind their desk, they would go out, take part and come back behind their desk and do the planning.

LAURENCE REES: And it was important to go out and be involved in the killing personally in order to show that you were strong?

NORBERT FREI: Yes. Exactly. To show that you are strong, that you can bear this. I mean, as Himmler says in his famous Posen speech, to do this and still to be honest, to be reliable, to be uncorrupted, I mean, he has his actual phrasing there, 'this is what makes us so great and so important in front of history'. He knows absolutely that he is lying because he knows about all this terrible corruption within the SS, but still this is how they explain it to themselves.

LAURENCE REES: And this is the idealistic goal.

NORBERT FREI: This is the idealistic goal, this is the way of putting it right in front of themselves despite the fact that this is also the Himmler who visits Auschwitz and vomits.

LAURENCE REES: But isn’t it supposed to be a sign of manhood for these Nazis to be able to see little children killed in front of them, because then they prove that not only do they have an intellectual gift but they are strong individuals as well?

NORBERT FREI: Yes. You are not doing this because of your individual hate of the Jews or because this particular Jew or this particular baby is something to be hated, you’re doing this for the sake of a greater thing, for the sake of a greater ideology, for the sake of a greater purpose.

LAURENCE REES: And for these Nazis the logic almost then becomes that if you love your own children you must kill these other Jewish children, because otherwise the Jews will create a race of avengers?

NORBERT FREI: Exactly. I mean, this is a perverse system but in itself not totally a-logical.

LAURENCE REES: The same people involved in the murders for ‘race hygiene’ questions - like the disabled - are then just simply transferred through to the extermination programme. Could you talk a little bit about why that is?

NORBERT FREI: There’s actually a link in terms of people and in terms of technology, if you want to call it technology. They were testing a couple of things when they were carrying out this so-called euthanasia programme in these clinics for the mentally ill within Germany, and these people who were carrying out these techniques were finally transferred to the East in order to erect special extermination camps. Not just within existing concentration camps but special extermination camps like Sobibor were created in order to kill as many people as possible in the shortest possible time. So these people were brought there by train and killed within a couple of hours. And for that you needed experts who built these gas chambers and to bring over this technology to the East, and these were the people from the euthanasia programme which started inside Germany.

LAURENCE REES: And they’ve developed a technology that means that they can then delegate a lot of the work to the Ukrainian guards and others.

NORBERT FREI: Yes. Well, the actual work is again done by auxiliary forces or even by the victims themselves. There were these Sonderkommandos, Jewish Sonderkommandos who actually had to do part of the work.