For a Jew to live as an Aryan - or on the "Aryan side", as people used to say referring to a geography which, in Warsaw, had a vast ghetto wall as a demarcation line - was no easy feat. It took, first of all, an act of premonitory imagination, a sense that, if Jews were being herded together, the consequences, this time, would be on a scale never yet seen. Jews, after all, had had a history of ghetto-isation, of living in their own quarters and surviving terror. In the early years of the Second World War, few foresaw the hideous scale that this particular pogrom was to take. Those who did usually belonged to a younger, more secular generation and one which could speak unaccented Polish.
The decision to disobey the order to enter the ghetto walls or to risk instant death by escaping them - ripping off the white armband and blue star that signalled Jewishness - led not to immediate freedom, but to a different world of danger.
In an occupied police state, identity papers become as crucial as food or fuel. ID checks were frequent and brutal. Procuring an Aryan identity was thus the first step towards dissimulating one's Jewishness. Blank baptismal certificates could be purchased on the black market. But "authentic" ones, supposedly official replacements for lost documents, were safer. In either case, a name, perhaps of someone recently dead, together with the name of a church, preferably destroyed, and, for good measure, the name of a priest, preferably dead, had to be found. Details had then to be typed out and authorised by a tame notary or an engraver who could create a good imitation of a notary's stamp. Each step required a fee. Armed with this the Jew could then register with the police and finally obtain the Kennkarte - the German-issued ID every Gentile had to carry.
Being blond was an asset in this, as in the rest of the business of survival. But it was hardly enough. Blondness didn't reach to cover the evidence of circumcision. Nor could it disguise fear that had become daily, habitual, instinctive dread - the wayward glance over one's shoulder, the hunched shoulders, the quick pace, almost a run. My dark-haired father, having escaped from the Warsaw Ghetto, stayed in hiding in a boarded-up warehouse room for several months in order to learn not only his catechism and saints' days, but how to look confident, unafraid, in preparation for the streets.
The streets were treacherous. Germans, it was said, could sometimes be duped. But Polish policemen had the noses of bloodhounds and could sniff out Jews. Well-paid informers and perfidious szmalcowniki or blackmailers trawled Warsaw for lucrative prey, squeezing out payments, before offering up their victims to the occupying power. Worst of all were the notorious lapanki, brutal round-ups in which whole blocks were cordoned off by armed SS and all able-bodied individuals were promptly shipped off to labour camps in Germany. Or worse.
Yet staying home was hardly an option. The healthy were meant to be at work, which entailed more documents. Neighbours grew suspicious of an idler, who could only be a Jew. In Poland, by October 1942, sheltering Jews had become a crime punishable by execution. The fact that the Nazis found it necessary to impose the death penalty in Poland and in no other occupied country suggests, against popularly received wisdom, that the Poles were more prone than other nations to helping the Jews.
Lisa Appignanesi is the author of `Losing the Dead' (Chatto & Windus, pounds 15.99) and `The Dead of Winter' (Bantam, pounds 9.99)