Mar Shmuel

Shmuel, called Mar Shmuel and Shmuel Yarhina'ah, "the astronomer", son of Abba bar Abba, headed the academy of Nehardea on the Euphrates, the oldest Jewish centre of Babylonia. He and his colleague Rav, who founded the academy of Sura, were the first great amoraim of Babylonia, and their debates, "Rav and Shmuel", run through the whole Talmud; the law follows Shmuel in civil matters and Rav in ritual ones. His best-known ruling is dina demalkhuta dina, "the law of the kingdom is the law" (Bava Kamma 113a, Nedarim 28a, Gittin 10b), which binds Jews to the just laws of the state they live in.

He was also a physician and an astronomer: "the paths of the heavens are as clear to me as the streets of Nehardea" (Berakhot 58b), and he said he could fix the calendar for the whole Diaspora without witnesses (Rosh Hashanah 20b). He lived under the Sasanian king Shapur I, and he died around 254; a few years later Nehardea was sacked by the Palmyrenes and its academy moved to Pumbedita. His rule of the law of the land still guides Jewish life in every country.