Yaakov Katz (1904-1998) - the largest Jewish historian and sociologist of the XX century. Born in Hungary, in 1936 he moved to Eretz Yisrael. He was a professor at the Hebrew University of Jerusalem. The author of many works on the history of Jews in Europe, the largest of them: "Exclusion and Tolerance," "Jews and Freemasons in Europe," "Emancipation and Assimilation," "Exodus from the Ghetto." Perhaps his most important book is Tradition and Crisis (1958).