Joseph Rosen (Yiddish: יוסף ראָזין, Yosef Rosin), known as the Rogatchover Gaon, ("Genius of Rogachev"), and also often referred to by the title of his main work Tzofnath Paneach ("Decipherer of Secrets"), (Rogachev, 1858 – Vienna, 5 March 1936), was a rabbi and one of the most prominent talmudic scholars of the early 20th-century, known as a genius (gaon) because of his photographic memory and ability to connect sources from the Talmud to seemingly unrelated situations. He has been described as the foremost Talmudic genius of his time.
He was born in Rogachev, now Belarus, into a Hasidic family of Chabad hasidim, and was educated in the local cheder (Torah school for small children). His unusual capabilities were noticed at the age of thirteen, when he was sent to study in Slutzk along with Rabbi Chaim Soloveitchik, five years his senior, under the Beis Halevi, Rabbi Yosef Dov Soloveitchik. He subsequently studied under Rabbi Yehoshua Yehuda Leib Diskin (Maharil Diskin) in Shklov. He then assumed (in 1889) the rabbinate of the Hasidic community in Dvinsk for almost 50 years, where his non-Hasidic counterpart was Rabbi Meir Simcha of Dvinsk; they served in parallel until the late 1920s, and enjoyed excellent relations.
Among those who received semicha (Rabbinic ordination) from him were the seventh Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson; Rabbi Mordecai Savitsky (1911-1991) of Boston; Rabbi Zvi Olshwang (1873–1959?) of Chicago, who was a brother-in-law of Rabbi Shimon Shkop; and Rabbi Avraham Eliyahu Plotkin (1888-1948), the author of Birurei Halachot (a copy of the actual semicha is included in that work).
The Rogachover is remembered for his breadth of Torah knowledge and caustic wit. He did not suffer inadequacy lightly. He was similarly reputed to rarely quote any rabbinic authority post-Maimonides, and avoided recent rabbinic works of the Achronim in favour of the Rishonim (those preceding the late 15th century). His responses to queries of Jewish law are generally enigmatic and cryptic.
Throughout his life, despite not being an official Lubavitcher Chassid, he maintained very close connections to Lubavitcher Chabad Chassidim and their Rebbeim, Rashab and Rayatz (after Rashab's death, he supported the decision to appoint the young Rayatz as the new Rebbe). The Rogatchover is a famous figure in Chabad Lubavitch folklore; his name often comes up in stories told in yeshivas and during farbrengens—content ranging from self-sacrifice and dedication to Torah values despite the pressures of Russian government, to special sensitivity of spiritual dimension of the Torah (in Chassidus and Kabbalah), to his genius in the revealed Torah. The Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson once quoted the Rogachover, who said that the whole Judaism to him could be condensed into ten basic ideas, and were he to be smarter, it would be only one idea.
The Rogatchover was a noted Talmudic scholar and published a number of his works on Talmud and Maimonides.
His main work, a commentary on Maimonides, was published during his lifetime, as were five volumes of halachic responsa. The remainder of his surviving writings appeared in the United States and Israel many years after his death; all are titled Tzofnath Paneach "decipherer of secrets", (a title given to the Biblical Joseph by Pharaoh (Genesis 41:45)). His manuscripts were smuggled out of Latvia in the form of micro photographs sent via mail to the Safern family in the Bronx at the outbreak of the World War II by his successor, Rabbi Yisrael Alter Safern-Fuchs (1911–1942), who remained in Latvia to complete this task, and his daughter Rachel Citron, who had come to Dvinsk from Eretz Yisroel to help preserve her father's manuscripts. Both died at the hands of the Nazis as a result. A portion of these manuscripts was edited and published by Rabbi Menachem M. Kasher. Seven manuscripts were published by Machon Tzofnas Paneah, headed by Rabbi Mordechai Pinchas Teitz. Machon Hamaor in Jerusalem is now publishing the remaining manuscripts.
The Rogatchover's works include responsa and novellae on Torah and Talmud. They are regarded as difficult and inaccessible, as he employs the philosophical terminology of Maimonides' Guide for the Perplexed even in non-philosophical analyses. Rabbi Kasher, therefore, included Mefa'aneach Tzefunoth, an explanatory commentary, to facilitate understanding of the Rogatchover's influential work.
The Rogatchover authored a number of works on Jewish law, some of which were published in his lifetime.
- Tzafnath Paane'ach – his magnum opus, a two volume commentary on Maimonides's Mishneh Torah
- Tzafnath Paane'ach al HaTorah – a five volume commentary on the bible
- Tzafnath Paane'ach al HaShas – a four volume commentary on the Talmud, covering tractates Bava Kamma, Bava Metzia, Makkos, Sanhedrin, Horayos
- Tzafnath Paane'ach Responsa – his responsa on Jewish law
- Shaalos Utshuvos Tzafnath Paane'ach Hachadashos – additional volumes responsa on Jewish law
- Chibur al Moreh Nevuchim – a commentary on The Guide to the Perplexed, published at the end of his commentary on the bible
- Michtvei Torah – correspondence between the Gaon and Rabbi Mordechai Kalina
- Blau, Rivka (March 2001). Learn Torah, Love Torah, Live Torah: Harav Mordechai Pinchas Teitz, the Quintessential Rabbi. NJ: Ktav Publishing House, Inc. pp. 36–37.
- HaRogatchover by Y. Borochov, 2005 p.22
- HaRogatchover by Y. Borochov, 2005 p.77-79
- The chapter on the Rogatchover in the newest edition (Jerusalem, 2006) is on pp. 73-140. See the chapter on "Or Sameah: Joyous Light and Tzofnat Paneah: Revealer of the Hidden" in "Learn Torah, Love Torah, Live Torah: HaRav Mordechai Pinchas Teitz, the Quintessential Rabbi" by Rivkah Blau (Ktav, 2001), pp. 33-51; it is an account by Rabbi Teitz of the Rogatchover's methods based on a term spent studying with him in 1931, and years of friendship between the Rosen and Teitz families. It is reprinted in the Hebrew version, "V'Samahta B'Hayekha" (Urim, 2006), pp. 25-34.
- Schwartz, Dovber. "The Rogatchover Gaon: A Study in Abstraction". Hakirah: The Flatbush Journal of Jewish Law and Thought.
- Tzafnat Pane'ach Institute - organization striving to research and republish Rosen's works
- The Rogatchover Gaon by Dovber Schwartz
- Schwartz, Dovber. "The Rogatchover Gaon: An Study in Abstraction". Hakirah: The Flatbush Journal of Jewish Law and Thought.