What is the hymn tune used in the Lux Aeterna of the Durufle requiem?

The hymn tune used in the "Lux Aeterna" movement of Duruflé's Requiem is the "In Paradisum" chant. This Gregorian chant is traditionally sung during the funeral liturgy as the deceased is led into paradise. Duruflé's setting beautifully incorporates this tune, blending it with rich harmonies to evoke a sense of peace and hope.