Gregorio Martínez Sierra was a prominent Spanish writer, poet, and dramatist active during the early 20th century. He was a key figure in the modernist movement in Spanish literature, known for directing theatrical works with innovative staging. However, much of his literary work is now widely acknowledged to have been written by his wife, the talented writer and feminist María de la O Lejárraga. Despite the complex authorship, his name remains associated with important theatrical pieces like 'Canción de cuna' (Cradle Song), which achieved international success.