Moses Mendelssohn was the first Jew to bring secular culture to those living an Orthodox Jewish life. He valued reason and felt that anyone could arrive logically at religious truths. He argued that what makes Judaism unique is its divine revelation of a code of law. He wrote many philosophical treatises and is considered the father of the Jewish Enlightenment.

Moses Mendelssohn was born in Dessau, a city in the state of Anhalt-Dessau in Germany, on September 6, 1729. As a child, he suffered from a disease that left him with a curvature of the spine. He was the son of a Torah scribe and his family was poor but learned. He began a traditional Jewish education under David Fraenkel, the rabbi of Dessau. When Fraenkel became rabbi of Berlin, the 14-year-old Mendelssohn followed him and studied in Fraenkel’s yeshiva in Berlin. He soon became a promising scholar of Talmud and Rabbinics. He is a relative of Samson Raphael Hirsch. He received free meals from neighborhood families and took on odd tutoring jobs. In addition to learning German and Hebrew in Berlin, Mendelssohn also studied French, Italian, English, Latin, and Greek. He took up other secular subjects, in which he excelled, including mathematics, logic, and philosophy. In the mid-1750s, he developed friendships with the philosopher Immanuel Kant and also with Gotthold Lessing, a dramatist, literary critic, and advocate of enlightened toleration in Germany. With Lessing’s encouragement, Mendelssohn began to publish philosophical essays in German. In 1750, Mendelssohn began to serve as a teacher in the house of Isaac Bernhard, the owner of a silk factory. That same year, Frederick the Great gave him the status of "Jew under extraordinary protection." In 1763, the Prussian Academy of Sciences awarded him a prize for his treatise on "evidence in the metaphysical sciences." Four years later, he became the bookkeeper of Bernhard’s firm and eventually a partner. Throughout his life, he worked as a merchant while continuing to write. In 1779, Lessing wrote the play Nathan the Wise in which a Jewish hero, modeled after Mendelssohn, appears as a spokesman for brotherhood and love of humanity. Mendelssohn modeled his philosophy after that of Christian Wolff (a prominent philosopher of the Enlightenment) and Gottfried Leibnitz (a European rationalist). He wrote some general philosophical works, including many dealing with the theory of art, but his most well-known writings deal with Judaism. Mendelssohn conceived of God as a perfect Being and had faith in God’s wisdom, righteousness, mercy, and goodness. He argued that "the world results from a creative act through which the divine will seeks to realize the highest good." He accepted the existence of miracles and revelation as long as belief in God did not depend on them. He also believed that revelation could not contradict reason. Like the deists, he claimed that reason could discover the reality of God, divine providence, and immortality of the soul. He was the first to speak out against the use of excommunication as a religious threat. At the height of his career, in 1769, Mendelssohn was publicly challenged by a Christian apologist, a Zurich pastor named John Lavater, to defend the superiority of Judaism over Christianity. From then on, he was involved in defending Judaism in print. In 1783, he published Jerusalem, or On Religious Power and Judaism. This study posited that no religious institution should use coercion and emphasized that Judaism does not coerce the mind through dogma. He argued that through reason all people could discover religious philosophical truths, but what made Judaism unique was its divinely revealed code of legal, ritual, and moral law. He said that Jews must live in civil society but only in a way that their right to observe religious laws is granted. He recognized the necessity of multiple religions and respected each one.

Mendelssohn wanted to take the Jews out of a ghetto lifestyle and into secular society. He translated the Bible into German, although it was written in Hebrew letters, with a Hebrew commentary called the Biur. He campaigned for emancipation and instructed Jews to form bonds with the gentile governments. He tried to improve the relationship between Jews and Christians as he argued for tolerance and humanity. He became the symbol of the Jewish Enlightenment, the Haskalah.

Mendelssohn's own descendants, the most famous being the composer Felix Mendelssohn, left Judaism for Christianity.

Sources: Dan Cohn-Sherbok, Fifty Key Jewish Thinkers, (New York: Routledge, 1997).
Max Dimont, Jews, God and History, (New York: Simon and Schuster, 1962).
Shanon Kleinman, "Who was Moses Mendelssohn?" Hamevaser.
Hans Kung, Judaism, (New York: Crossroad, 1992).
Robert Seltzer, Jewish People, Jewish Thought, (New York: Macmillan Publishing Co., 1980).