Yesodi HaDa'at by Rabbi Moshe Rosenstein, Warsaw 1935. First edition, handwritten dedication and signature of the Mashgiach of the Lomza Yeshiva Rabbi Moshe Rosenstein, 'to the memory of the world I send our dear book to my friend and loved ones, the dear and generous, Mr. Mordecai Delawitz, my friend and beloved forever, Moshe Rosenstein (Mashgiach in the Yeshiva of Lomza)'. His book, "Yesodei HaDa'at," which is one of the basic books of the Mussar movement, caused a minor scandal when, in a certain section of the book, Rabbi Rosenstein shared the words of Maimonides that the Israelites believed in Moses not by virtue of the signs he gave. In the next part of the book he hastened to correct things and made it clear that actually came only to interpret the true intention of Maimonides. The copy before us contains two deletions in four words within the section dealing with the words of the Rambam, which may have been done by him. The Ga'on Rabbi Moshe Rosenstein [1841-1941] began his way at the Yeshiva of Telz while the Mussar movement did not enter the yeshiva at that time. When he met the saintly Rabbi Yerucham from meir, who was studying at the Kelm Yeshiva at the time. He persuaded him to come and study there. Where Rabbi Moshe began his study of musar. Later he studied at the Kollel Yeshiva of the Radin, headed by the Chofetz Chaim. In 1912, he was appointed mashgiach at the Lomza yeshiva until the end of his life. During his tenure as mashgiach, the yeshiva prospered and grew. Rabbi Moshe was known for his methods of asceticism and celibacy - and he used to spend almost the entire week in the yeshiva, and only during the Sabbath meals was he at home. Many of the students in Lomza came from Poland and were from Hasidic homes. At first it was difficult for them to adjust to the path of the 'musar', but many of them "called him with love and great mental admiration," as one of his students testified, and even realized his influence. 66 p., 22 cm. The leaflet is detached, the upper corner of the cover is cut and glue. fine condition.