The renowned Clarion Choir returns to the Met Live Arts series to perform Thomas Tallis' 'Christmas Mass' - Missa Puer Natus Est - a seven-part masterpiece, written during the reign of Mary I, and combining elements of the English and Spanish styles. The Mass is based on the plainchant melody of the same name, meaning 'A Boy is Born,' which serves as an Introit for one of the Masses on Christmas Day. Interspersed with movements from the Mass, Clarion will also sing some of Tallis' most beloved short motets, such as 'If Ye Love Me' and 'O Nata Lux,' which represent the different styles the composer employed as rulers and rules changed over the course of his long career.