MENDELSSOHN, MOSES (1729-1786), Jewish philoso pher, was born in Dessau in 1729. His father's name was Mendel, and he was later on surnamed Mendelssohn (=--son of Mendel). Mendel Dessau was a poor scribe, and his son Moses in his boy hood developed curvature of the spine. His early education was cared for by his father and by the local rabbi, David Frankel. The latter, besides teaching him the Bible and Talmud, introduced to him the philosophy of Maimonides (q.v.). Frankel removed to Berlin in 1743, where Mendelssohn joined him a little later. With his scanty earnings he bought a Latin copy of Locke's Essay con cerning the Human Understanding, and mastered it with the aid of a Latin dictionary. In 1750 he became tutor to the children of a wealthy silk-merchant, Isaac Bernhard, who made the young student successively his book-keeper and his partner. In 1754 he was introduced to Lessing. Just as the latter afterwards makes Nathan the Wise and Saladin meet over the chess-board, so did Lessing and Mendelssohn actually come together as lovers of the game. Lessing had already begun his work of toleration, for he had recently produced a drama (Die Juden, 1749), the motive of which was to prove that a Jew can be possessed of nobility of character. This notion was being generally ridiculed, but Lessing found in Mendelssohn the realization of his dream. Mendelssohn had written in lucid German an attack on the national neglect of native philosophers (principally Leibnitz), and lent the manu script to Lessing. Without consulting the author, Lessing pub lished anonymously Mendelssohn's Philosophical Conversations (Philosophische Gespriiche) in 1755. In the same year there appeared in Danzig an anonymous satire, Pope a Metaphysician (Pope ein Metaphysiker), the joint work of Lessing and Mendels sohn. Mendelssohn now became (1756-59) the leading spirit of Nicolai's important literary undertakings, the Bibliothek and the Literaturbriefe, and ran some risk (which Frederick's good nature obviated) by somewhat freely criticizing the poems of the king of Prussia. In 1762 he married Fromet Gugenheim, who survived him by 26 years. In the year following his marriage Mendelssohn won the prize offered by the Berlin academy for an essay on the application of mathematical proofs to metaphysics, although among the competitors were Abbt and Kant. In Oct. 1763 the king granted Mendelssohn the privilege of Protected Jew (Schutz Jude)—which assured his right to undisturbed residence in Berlin.
As a result of his correspondence with Abbt, Mendelssohn resolved to write on the immortality of the soul. His Phaon (1767) was modelled on Plato's dialogue of the same name. Men delssohn's work possessed some of the charm of its Greek exemplar. The book was translated into nearly all the European languages, and its author was hailed as the "German Plato," or the "German Socrates."
Mendelssohn resolved to devote his life to the culture and the emancipation of the Jews. He began by his German translation of the Pentateuch and other parts of the Bible. This work (1783) constituted Mendelssohn the Luther of the German Jews. From it, the Jews learned the German language; from it they imbibed culture; with it there was born a new desire for German national ity; as a result of its popularity was inaugurated a new system of Jewish education. Mendelssohn was the first great champion of Jewish emancipation in the 18th century. He put forward his plea for tolerance in Jerusalem oder 'fiber religiose Macht and Judenthum (1783; Eng. trans. 1838 and 1852). He asserted the pragmatic principle of the possible plurality of truths : that just as various nations need different constitutions—to one a monarchy, to another a republic, may be the most congenial to the national genius—so individuals may need different religions. The test of religion is its effect on conduct. This is the moral of Lessing's Nathan the Wise, the hero of which is undoubtedly Mendelssohn. Having been taught that there is no absolutely true religion, Mendelssohn's own descendants—a brilliant circle, of which the musician Felix was the most noted—left the synagogue for the church. But despite this, Mendelssohn's theory was found to be a strengthening bond in Judaism.
Mendelssohn's Morgenstunden, oder fiber das Dasein Gottes appeared in 1785, and he died as the result of a cold contracted while carrying to his publishers in 1786 the manuscript of a vindication of his friend Lessing, who had predeceased him by five years.
Mendelssohn had six children. His sons were : Joseph (founder of the Mendelssohn banking house, and a friend and benefactor of Alexander Humboldt), whose son Alexander (d. 1871) was the last Jewish descendant of the philosopher ; Abraham (who married Leah Bartholdy and was the father of Fanny Hensel and J. L. Felix Mendelssohn-Bartholdy) ; and Nathan (a mechanical engi neer of considerable repute). His daughters were Dorothea, Recha and Henriette, all brilliantly gifted women.
See the biography by his grandson G. B. Mendelssohn prefixed to his Seimtliche Werke (7 vols., Leipzig, 1843-44) and by M. Brasch in the edition (2 vols., Leipzig, 188o) of his Schriften zur Philosophie, Aesthetik und Apologetik; also M. Kayserling, M. Mendelssohn's Leben und Wirken (2nd Leipzig, 1888), and Moses Mendelssohn Ungedrucktes and Unbekanntes von ihm and caber ihn (2nd ed., Leipzig, i888) ; L. Goldstein, Moses Mendelssohn and die deutsche (Konigsberg, 1904) ; H. Scholz, Die Hauptschriften zum Pantheismusstreit zwischen Jacobi und Mendelssohn (1916).