The twelfth century in Europe, hailed by historians as a time of intellectual and spiritual vitality, had a dark side. As Robert Chazan points out, the marginalization of minorities emerged during the "twelfth-century renaissance" as part of a growing pattern of persecution, and among those stigmatized the Jews figured prominently.
The migration of Jews to northern Europe in the late tenth century led to the development of a new set of Jewish communities. This northern Jewry prospered, only to decline sharply two centuries later. Chazan locates the cause of the decline primarily in the creation of new, negative images of Jews. He shows how these damaging twelfth-century stereotypes developed and goes on to chart the powerful, lasting role of the new anti-Jewish imagery in the historical development of antisemitism.
This coupling of the twelfth century's notable intellectual bequests to the growth of Western civilization with its legacy of virulent anti-Jewish motifs offers an important new key to understanding modern antisemitism.
In medieval Northern Europe, Jewish populations rose and fell quite rapidly: as this book explains, there is little evidence of Jewish settlement in England and northern France until around 1000, but 300 years later Jews had been expelled from both places.
In this short book, Chazan tries to explain what went right (and wrong). This is the story he tells: In 1000, England and France were backwaters. These places became more integrated into the rest of Europe and thus more prosperous. Jewish traders moved there in search of commercial opportunities, and were already buying and selling goods on credit. It was a small step from selling on credit to becoming a full-time moneylender, and some Jews did that and became wealthy; as the economy expanded, sizable sums of capital were necessary to finance these things, and some Jews had that capital. And because the Church opposed usury, Christians could not lend money at interest, which means Jews had little competition. At first, monarchs supported Jewish moneylenders by enforcing contracts, because they wanted access to Jewish capital.
But this prosperity contained within it the seeds of its own demise. Borrowers of all sorts resented having to repay debts, and kings realized that they could get wealth in an instant by confiscating Jewish wealth. And traditional Christian hostility towards Judaism made Jews even more unpopular than non-Jewish moneylenders would have been. So in the 13th century, kings first began to impoverish Jews by taking their wealth, and ultimately expelled them. In addition, popular hostility towards Jews began to grow as well; Chazan takes note of this, but I'm not sure he satisfactorily explains why Christians were more likely to think Jews were evil and dangerous in 1250 than they did in 1150- perhaps because it is impossible to know.