ר׳ יעקב בן משה הלוי מולין

ר׳ יעקב בן משה הלוי מולין (c.1360–1427), the מהרי״ל or מהר״י סג״ל, was the foremost late-medieval authority on the customs of Ashkenaz. Born in Mainz to its rabbi ר׳ משה הלוי מולין, he studied with his father and later in Austria under scholars including ר׳ שלום מנוישטאדט. Returning to Mainz after his father's death, he led the community and founded a major yeshiva whose students included ר׳ יעקב וייל. Communities across Germany, Austria and Bohemia addressed halakhic questions to him. During the crises surrounding the Hussite wars and persecution of Jewish communities, he organised prayer, fasting and communal relief. He was also a renowned prayer leader who insisted on preserving inherited liturgical melodies. His practices, rulings, sermons and melodies were recorded by disciples, especially ר׳ זלמן משט־גואר, in מנהגי מהרי״ל, first printed posthumously in 1556. That work became a foundation of Western Ashkenazi practice and was repeatedly cited by later authorities. Late in life he moved to Worms, where he died and was buried in 1427.