As I was going through security, I wondered, why Frankfurt? It was only once I was on the plane that I remembered. According to his military record, Hans Schiller studied Chemical Engineering at the Johann Wolfgang Goethe-Universität, at Frankfurt am Main. The rest I had deduced or discovered from my research. I read that it was in the laboratories of the industrial chemical group IG Farben, with the support of the Johann Wolfgang Goethe-Universität, under the direction of the sinister Nebe, head of Einsatzgruppe B, that they had developed Zyklon B, the poison used in the gas chambers. From the moment I found out, I couldn’t help but wonder whether Papa, who had just finished his degree at the time, was somehow involved in the research and in the endless arguments that the proposal to gas camp prisoners had triggered among the dignitaries, the intellectuals and the bleeding hearts of the Third Reich. The problem they were fretting over was this: having decided to gas the Lebensunwertes Leben – Jews and other Minderwertige Leute, the mentally handicapped, the ill, the gypsies, the homosexuals – should the procedure be humane, or were the results all that mattered? The first approach, the humane solution, called for the use of odourless gas, or, better still, prussic acid which has a sweet smell, something IG Farben produced in industrial quantities for agricultural and domestic purposes, for fumigating grain stores and for domestic rat poison. Those being gassed would feel nothing, would not know they were dying, at a certain point they would simply drop like flies and it would all be over. This would be the most humane way to kill them, eine der humansten Tötungsarten. Moreover it would spare their killers much of the horror of the work. But it turned out that this method posed a serious risk to German soldiers and those who operated the gas chambers, the Sonderkommodo – camp prisoners who were subjected to the torment of having to remove the bodies of their brothers and take them to the crematoria – since they might venture into the chambers after a batch of killings and be poisoned without realising it. Others – and these were the people who won the argument – were in favour of making the gas highly irritating by the addition of an odorant – Warnstoff – which would alert them to any residual gas in the chambers or to any leaks when handling gas canisters. The choice, they maintained, was between the soldier and the prisoner, between the safety of the former and the comfort of the latter. The problem having been formulated in such a way that it led naturally, humanely, to favouring their own, they decided this would be the wisest course of action. Those being gassed would suffer terribly, but since the eventual intention was to kill them and burn their bodies, this minor inconvenience hardly mattered and was morally acceptable. To placate more sensitive souls, they decided on a ruse: those taken to the gas chambers would be told that they were going to shower, this way they would be happy and grateful. But this is the sort of ploy you can only use once. Word quickly spread in the camps, everyone knew everything. Eventually, this hollow promise was reserved for those newly arrived: the worthless, the old, the children, the pregnant women, the sick and the handicapped who would be only too happy to believe it.