MANASSEH BEN (Porat) JOSEPH OF ILYA (1767–1831), one of the forerunners of the *Haskalah in Lithuania and Russia. He was born in Smorgon, Lithuania, and was renowned as a child for his remarkable memory and intellectual precocity. He received a talmudic education in the home of his father, who was a dayyan. In 1784 he married and went to live in the house of his father-in-law, a wealthy merchant in Ilya. Manasseh was among the disciples and intimates of *Elijah b. Solomon Zalman, the Gaon of Vilna, and became friendly with Joseph Mazal from Viasyn, who owned an excellent Hebrew library including scientific and research works. Gradually he reached theoretical and practical conclusions tending toward increasing rationalism and called for some change in halakhah. In his works, his attitude to Talmud study is based on these conceptions. In several places, for example, he challenged the Talmud and Rashi's understanding of certain pronouncements of the Mishnah. He regarded natural sciences with respect and was critical of the Kabbalah. Demanding the abrogation of halakhic commands that were not an integral part of the basic, early law and that people could not carry out in actual life, he advocated the principle of alteration and leniency in halakhah, according to changing trends. He likewise called for a changed and orderly curriculum of traditional studies (see also *Judah Loew b. Bezalel): first the Bible, Mishnah, and Gemara and, for talented youth, secular studies as well.
Manasseh has been credited with the invention of several agricultural machines which the unsophisticated environment rejected. Raising the problem of the poor in Jewish society, he called for justice for them, as "the overwhelming majority of these people lack their basic needs, are hungry and thirsty, have no garment against the cold, and their spirit is faint within them." Social responsibility and service for society he regarded as a duty, even at the cost of personal advantage. He attacked the custom of kest, by which a newly married couple was supported for several years by the wife's parents, since he was in favor of productivization. Regarding trade as "robbery," he called for "proper leadership" to enable the Jewish masses to earn their livelihood through crafts. From time to time he suggested that the leading rabbis confer to deliberate on the problems of a "general improvement" of Jewish conditions and culture. Manasseh was persecuted. A rabbinical convention deliberated his excommunication and he was prevented from going to Berlin. He therefore completed his studies in the Polish and German languages at home and read antiquated scientific works in those languages, thus gaining a sketchy knowledge in this field. To make a living, he later worked as a private teacher in various places in Russia and Galicia. It was then that he became acquainted with Nachman *Krochmal and other Galician maskilim.
Manasseh was a prolific writer, but it was not easy for him to publish his writings, because none of them was issued with approbation of the rabbis. His Pesher Davar (Vilna, 1807) was burnt by many rabbis. When he attempted to publish his principal work, Alfei Menasheh, in Volhynia, the printer burned the manuscript and the copies that had already been printed as soon as he became aware of the content of the work; when it was printed in Vilna (1822), the author was required to omit a paragraph which alluded to reforms in halakhah. His Binat Mikra (Grodno, 1818), written in the form of unsystematic novellae, deals with the cantillation marks of the Bible as factors in syntax and meaning. In his pamphlet Sama de-Ḥayyei (Yid. trans. Lebn-Mittel), he sought to present his views to the people at large and to outline "proper and useful behavior for life in this world." Though he had intended to publish additional pamphlets, no more appeared, possibly because of the opposition of the rabbis and community leaders. After Sama de-Ḥayyei, Manasseh published anonymously the pamphlet Shekel ha-Kodesh, in which he apologized to those who considered him "a nonconformist in several matters," and suggested that his opponents "choose several men who would be willing to clarify their opinions with me."
Manasseh visited ḥadarim and encouraged young men to study mathematics and sciences. In 1827 the Jews of his native town elected him as their rabbi, but he resigned after a year, refusing to be involved in the cruelty of the *Cantonist mobilization. He died in a cholera epidemic. Most of his literary remains were destroyed in the fire which broke out in Ilya in 1884, but some extracts appeared in the second volume of Alfei Menasheh (1904), published by his grandson Isaac Spalter, head of a yeshivah in Smorgon. Circles of pupils and admirers cherished his memory, and using this tradition, M. *Plungian, one of the first Lithuanian maskilim, wrote his biography of Manasseh, Ben-Porat (Vilna, 1858). *Maskilim of the 19th century (M. *Lilienblum, R.A. *Braudes, and others) used Manasseh's opinions against rabbis of the old school.
S.I. Stanislawski, in: Ha-Shilo'ah, 18 (1908), 274–7; S. Rosenfeld, in: Ha-Tekufah, 2 (1918), 250–88; Z. Rejzen, Fun Mendelsohn Biz Mendele (1923), 183–260; Zinberg, Sifrut 6 (1960), 153–61; Klausner, Sifrut, 3 (1953), 25–32; B. Katz, Rabbanut, Ḥasidut, Haskalah, 2 (1958) 187–203; R. Mahler, Divrei Yemei Yisrael ba-Dorot ha-Aḥaronim, 4 (1956), 63–68.