Ingmar Bergman (b. 1918) reached the absolute zenith of his creative powers with this radical 1966 masterpiece. Set against the harsh, windswept shores of a stony Fårö island cottage, the narrative transcends the archetype of the dutiful nurse tending to a silent patient. As their identities blur, the title's Latin origin—meaning the theatrical mask worn by actors—suggests a terrifying fusion of souls. Where does the performer end and the spectator begin?