Suor Leonora d'Este (1515-1575), Lucrezia Borgia's daughter, was a princess, a nun, and a musician. She left little to illuminate her history, but an obscure book of motets may at least help us understand her musical life: the Musica quinque vocum motteta materna lingua vocata, published in Venice in 1543. The book is anonymous, but it contains clues to its origins that lead us to the door of Leonora d'Este's home, the convent of Corpus Domini in Ferrara, perhaps even suggesting that she was its unidentified composer. The music here is the earliest published polyphony for nuns. This recording by Musica Secreta and Celestial Sirens allows it to be heard for the first time through carefully researched performances.