Leon Mandelstamm, (Aryeh Loeb; 1819–1889) the translater whose work I here criticized was a writer and adherent of the Haskalah in Russia. He was the fourth son of Joseph Mandelstamm, a man of liberal and progressive views who had imbibed German ideas and collected German books during his business travels in Germany. Under the guidance of his father and older brothers Leon acquired a large amount of rabbinical and secular knowledge before he was fifteen years of age. He married while very young, and settled with his wife's parents in Keidany, government of Wilna; but his progressive thoughts and habits were considered heretical there, and he was compelled to divorce his wife after about six months of married life.

In 1840 he became the first Jew to enroll at a Russian university (Moscow) and in 1844 graduated in oriental languages from the University of St. Petersburg. His research concerned the history of political regimes in ancient Israel. During his student years, he produced a book of poetry in Russian (1840). In 1846, after further studies at German universities, Mandelstamm was appointed in charge of Jewish affairs in the Ministry of Education in succession to M. Lilienthal. He was mainly concerned with establishing a network of government schools for Jews, and supervising the Jewish heder and talmud torah schools. For this purpose he traveled extensively throughout the Pale of Settlement and prepared textbooks; these were published by means of funds raised through the candle tax, and even private Jewish teachers were required to buy them. The books, which contained texts accompanied by German translations, included selections from the Mishnah, an anthology of Maimonides' writings, the Bible along with the Biur of Moses Mendelssohn and his pupils, and the Kevod Melekh of R. Jehiel Heller, which stressed the Jew's religious duty to respect secular kings and rulers. Mandelstamm was dismissed in 1857 as a result of attacks by his opponents among the maskilim and wealthier Jews of St. Petersburg who accused him of wasting funds and engaging in activities for his own profit. During his period in office, Mandelstamm corresponded with and met Haskalah leaders and prominent Hebrew writers, often arranging for them to be given posts. After losing his job, he lived for many years in Germany where he engaged in trade and in contracting. He wrote for both the Jewish and general press, and published, in German, several collections of studies in Bible and Talmud. The translation of the Pentateuch into Russian which Mandelstamm had produced in Germany was forbidden in Russia because of the general prohibition on scriptural works which were not approved by the Church. In 1872, however, permission was given to import and reprint his work there, provided that the translation was accompanied by the original Hebrew version. Toward the end of his life Mandelstamm returned to St. Petersburg where he died forgotten and in poverty.