הרב יוסף רוזין

Joseph Rosen known as the Rogatchover Gaon and Tzofnath Paneach, was an Ashkenazi rabbi and one of the most prominent talmudic scholars of the early 20th-century. Rosen was known as a gaon (genius) because of his photographic memory and tendency to connect sources from the Talmud to seemingly unrelated situations. Rosen has been described as the foremost Talmudic genius of his time. He is also estimated to have written some 50,000 responsa, making him the most prolific responsa-writer in Jewish history.