MOTZKIN, LEO (Aryeh Leib ; 1867–1933), Zionist leader and protagonist of the struggle for Jewish rights in the Diaspora. Born in Brovary, near Kiev, Motzkin received a traditional Jewish education and witnessed in his youth the Kiev pogrom in 1881. He studied in Berlin where he was among the founders of the Russian-Jewish Scientific Society (1887), whose members were Jewish students from Russia and Galicia who supported the *Ḥibbat Zion movement. They conducted heated debates with the majority of the Russian Jewish students, who were attracted to socialism and cosmopolitanism. When he completed his studies, Motzkin abandoned his opportunities for a scientific career and devoted himself to activities for the Jewish national cause. He was one of the strongest critics of the methods of Ḥovevei Zion and, with the appearance of Theodor *Herzl, Motzkin immediately joined the newly formed Zionist Organization at the First Zionist Congress and headed a group of delegates that demanded a clear and decisive wording of the *Basle Program. Before the Second Congress, Herzl sent him to Ereẓ Israel, and in his report to the Congress Motzkin criticized the settlement methods of Baron de *Rothschild and the Ḥovevei Zion and called for a political agreement with the Ottoman government. Despite his ideological closeness to Herzl, he joined the *Democratic Fraction, which he represented at the Fifth Zionist Congress (1901) and at the Conference of Russian Zionists in Minsk (1902). He kept aloof from the controversy over the *Uganda Scheme because of his deep attachment to Ereẓ Israel, on the one hand, and the urgent need to help the oppressed Jewish masses, on the other.
In 1905 Motzkin anonymously edited the revolutionary Russian Russische Korrespondenz, which was published in Berlin and provided West European newspapers with information on Russia in a radical spirit. He dedicated considerable space to the fate of the Jews and the anti-Jewish excesses. The Zionist Organization requested Motzkin to publish a book on the wave of pogroms in Russia; it was written for the most part by Motzkin himself (signed A. Linden) and was published in two parts in 1909–10 under the name Die Judenpogrome in Russland. The book contained thorough research into anti-Jewish violence in Russia from the beginning of the 19th century to its climax during the Russian Revolution of 1905–06, including descriptions of pogroms in various areas and towns and stressed the role of Jewish *self-defense. In 1912 Motzkin's pamphlet The Legal Sufferings of the Jews in Russia came out in an English translation by an anonymous author. It was also distributed in Russian among the Duma delegates in St. Petersburg. During the *Beilis trial (1911–13), Motzkin organized an information service in West European countries and Russia and spurred public figures to speak out against the blood libel. At the same time, he was a leading activist in the Hebrew language movement and among the first to speak Hebrew at conferences and meetings devoted to this subject. During World War i, he was head of the Copenhagen Office of the World Zionist Organization and the liaison between the various Zionist organizations in the warring countries. At the end of 1915 he left for the United States to mobilize support for the Jewish war victims on the East European front, and also for the struggle to ensure equal rights for the Jews of Russia. At the end of the war, Motzkin demanded that the Zionist Movement also concern itself with the civil rights of the Jews in the Diaspora. Thus, he took a leading part in the establishment of the *Comité des Délégations Juives at the Paris Peace Conference, to which various Jewish bodies were affiliated, including the World Zionist Organization, and which later became a standing institution at the League of Nations, serving as a world Jewish representative for all affairs other than those connected with Ereẓ Israel. In the following years as well, Motzkin continued to direct the committee, which concerned itself particularly with the struggle against antisemitism (inter alia with the legal defense of Shalom *Schwartzbard for the assassination of Simon *Petlyura, who was held responsible for the pogroms in the Ukraine) and with the defense of Jewish rights. For this purpose he was active in the movement supporting the League of Nations and in the international Congresses of National Minorities. He did not abandon his Zionist work, however, and served as permanent chairman of the Zionist General Council and of many Zionist Congresses.
When the Nazis came to power in Germany, Motzkin headed the anti-Nazi struggle of the Jewish people and brought the oppression of German Jewry before the League of Nations. When, under pressure from the German ethnic minorities in other countries, the Congress of National Minorities refused to deliberate on the situation of German Jews under the Nazis, Motzkin withdrew from the organization. He died in the midst of feverish activity to ensure political and financial aid to German Jewry. In 1939 Sefer Motzkin, including a selection of his writings and speeches, was published together with a monograph on him by the editor, A. Bein.
His son theodore samuel (1908–1970) was a mathematician and educator. Born in Berlin, from 1936 to 1948 he taught at The Hebrew University, Jerusalem. He settled in the United States in 1948 and was a research fellow of Harvard University from 1948 to 1950, after which he was a professor and research mathematician at the University of California. He contributed to the subjects of inequalities, approximation, polynomials, and geometry. He wrote Contributions to the Theory of Linear Inequalities.
S. Kling, in: Herzl Year Book, 2 (1959), 228–50; L. Lipsky, A Gallery of Zionist Profiles (1956), Ha-Olam (Nov. 16, 1933).