First spoken by medieval Jews living on the Rhine, it is thought that Yiddish grew out of German (though linguists such as Paul Wexler have offered contrasting theories). It quickly came to embody a distinct Jewish identity: written in the Hebrew script, it shares many terms with Hebrew. Its Eastern European variety—where most Yiddish-speakers once lived—also borrows from local Slavic languages. Práven, a word derived from the Slavic verb “to celebrate”, can be used in Yiddish to denote any happy occasion. This diversity gives Yiddish an incredibly subtle vocabulary. The language has three different words for “important” one each from German, Hebrew and Slavic (the Hebrew-derived term is associated with human or social importance, while the Slavic word has a more intimate tone). This vibrancy, moreover, helped spread Hasidism, a Jewish revival movement which enthusiastically used Yiddish in its religious writings.