Prominent Rabbinic leader and authority (1713–93). Landau was born in Poland but in 1755 was invited to become Rabbi of Prague, a position he occupied until his death. Landau, although he had studied Kabbalah in his youth, was opposed to its study except by the most erudite because of the danger of Shabbateanism (see SHABBETAI ZEVI), a movement which relied on the Kabbalah for its heretical approach to Judaism. He disliked the use of Kabbalistic terminology in Hasidism and had little regard for the unlearned Hasidim whom he accused of spiritual arrogance in adopting the mystic way reserved for the initiates.
Landau's fame rests chiefly on his Noda Biyhudah (‘Known in Judah’), a voluminous collection of Responsa in which he replied to Rabbis and other scholars from many parts of the Jewish world. Landau's legal decisions still enjoy great authority for Orthodox Jews.