Jakub Šimon Jan Ryba (1765–1815), also known by several surnames including Poisson and Peace, was a Czech composer and teacher renowned for his deep influence on Czech classical music. Born in Přeštice near Plzeň into a poor teaching family, he demonstrated early musical talent and studied in Prague. Despite aspirations for a greater musical career, he spent most of his life working as a village schoolteacher, often facing financial hardship and conflict with local authorities. His most celebrated work is the Czech Christmas Mass "Hey, Master," a beloved piece still performed annually across Bohemia. Although Ryba composed numerous pastorellas and masses, few aside from his Christmas Mass remain widely recognized today. His life ended in tragedy due to personal struggles, but his legacy endures through his cherished Christmas music.