Rabbi Nathansohn was born at Berezhany (Berzan), Galicia (today's western Ukraine); he was the son of Aryeh Lebush Nathanson, rabbi at Berzan and author of "Bet El." He studiedTalmud at Lviv (Lemberg) together with his brother-in-law Mordecai Zeeb Ettinger. In the 1830s in Lemberg—then under the rule of the Austrian Empire—he founded an informal study-group under his tutelage; this “yeshiva” attracted some of the most brilliant students in Galicia. In 1857 Nathanson was elected rabbi of Lemberg, where he officiated for eighteen years. He was a widely recognized rabbinical authority, and was asked to rule on various contemporary issues; his rulings are still widely cited (for instance he was one of the first to permit the use of machinery in baking Matzah, which created a widespread halachic controversy). Nathanson was very wealthy, and was known for his activity as a philanthropist. He died at Lemberg March 4, 1875.
Rabbi Nathanson was a voluminous writer, the author of many works, including:
"Mefareshe ha-Yam" (Lemberg, 1828), in cooperation with his brother-in-law Mordecai Zeeb Ettinger: notes by Joshua Heschel on the "Yam ha-Talmud," to which they appended their own responsa - HebrewBooks.org