the fateful year 1648. The great slaughter of Jews which took place then, beginning eight years of desperate troubles for the Jews of eastern Europe, was by far the worst outbreak of anti-Semitism since the First Crusade. Hitherto, the trend of Jewish emigration had been eastward, for hundreds of years. Now the trend was reversed. Though the teeming Ashkenazi community in eastern Europe continued to grow in numbers, and to a limited extent in prosperity, it never looked really safe again. For security, the more enterprising Jews began to turn their gaze to the West.
