Career
He specialized in Jewish demography and economic history. Born near Kiev, he received a traditional Jewish education. As a teenager, he was deeply moved by Hebrew writer Ahad Ha"american
After university study in Switzerland for a decade, he returned to Russia in 1913.
After being imprisoned in the aftermath of the October Revolution, he left Russia in 1921 for Berlin. There he was a correspondent for the New York Yiddish daily Forverts, a role he continued for more than 40 years.
He left Germany for Warsaw in 1934, emigrated to the United States in 1938, and finally to Israel in 1959. He also edited the Bleter far yidisher demografye, statistik, un ekonomik, which appeared in Berlin from 1923 until 1925, and the Economic-Statistical Section publications Ekonomishe shriftn and Yidishe ekonomik.