The Jewish cultural life in Iberian peninsula during the 10th and 11th centuries is often labelled as the Golden Age. It was the time of all-embracing efflorescence both in the field of letters and exact sciences, in which the Jew took an active part. But to what degree was this efflorescence among the Jewish community perceived by their Muslim neighbours? Sācid al-Andalusī’s Tabaqat al-umam, almost the only Muslim book describing the Jewish science, reveals that it was hardly noticed.