I think I've told readers before that, in many ways, I barely qualify to write this column. I was brought up knowing only that my father was "Jewish", that my grandmother spoke a peculiar language (it didn't help that she'd often leave her teeth out) and that my Uncle Joe - who came round every Boxing Day, did not celebrate Christmas.

As I got older, I gradually got to know more about where that mysterious "ish" had come from. Bearing this name, it often seemed that others presumed they understood far more about me than I did about myself. This still happens, and usually not in a good way.

Anyway, at one point, I began to wonder about that people to whom I was linked - "the Jews" (a dangerous folk, as opposed to the vanilla "Jewish community"), in a historical sense. What had European Jewry been like and what had been lost? Over time, this took on the appearance of a blurred-edged kaleidoscope of romantic images: shtetls, Yiddish theatre, urbane German Jews, chic French Jews, learned folk, red-haired women, libraries, Viennese psychoanalysts and - like my grandparents – illiterate crafts-people. All brought to an end by the Holocaust.

This week, through my letter box in one of the leafier parts of the diaspora, came the historian Bernard Wasserstein's new book, On the Eve, the Jews of Europe Before the Second World War. As I read it, the romanticism and the illusions began to be dispelled. Instead of only seeing "what was lost", I started to have a real view of what was happening to European Jews between the wars.

Wasserstein writes that Jews - "defined inclusively as that person who considered him or herself or was considered by others to be a Jew" - were a population of 10 million in Europe by the late 1930s. There were 3.2 million in Poland, three million in the USSR, with large communities in Romania and Hungary. In 1939, there were 381,000 Jews in Warsaw - more than in the whole of Greater Germany. (I love this fact: despite making up a third of Warsaw's population, the Jews provided, in 1925, less than 0.01 per cent of its arrested drunks.)

Jews made up less than 0.01 per cent of the drunks

Jews across the Continent were under-represented in agriculture, heavy industry, the civil service, the armed forces, academia (especially in Poland), and were concentrated in small commerce. Many were in the professions of law and medicine, very few were the plutocrats who got so much attention.

Though (or perhaps because) they were great institution builders, creating societies and charities, European Jews were riven by division. Far from there being a Jewish lobby, the Litvak and Galitzianer, Chasidim and Mitnagdim, the city Jews and the country Jews, had little to do with each other.

But the terrible thing is that, even before the Holocaust, the Jews were in decline. "By 1939," writes Wasserstein, "European Jewry was close to terminal collapse." Due to antisemitism, or a modern desire to shrug off old custom, Jews dis-identified. They married out, emigrated and either converted or brought up their children as non-Jews. They stopped speaking Yiddish and Ladino."

And everywhere their birth-rate fell. In that sense, says Wasserstein, they were "much less assimilators to existing social patterns than pioneers of the demographic transition that, over the next two generations, was to transform European society as a whole". In the eight years before Hitler came to power German Jewry had shrunk by 11 per cent. Hungary's declined from 473,000 in 1920 to 400,000 by 1939. In the enclaves of Lodz and Kovno the Jewish populations stagnated in poverty.

Myself, as a secular part-Jew, I feel caught between understanding and regret. I like the idea of post offices, pubs and libraries, but I don't use them. I have never participated in Pesach but I wish you Gut Yontiff from the bottom of my heart.