“Pie Jesu” means “Merciful/kind Jesus”; in its context in the Latin Requiem Mass, it calls on “the Lamb of God” to show mercy to the suffering. Kindness and mercy are at the heart of spirituality.
The text has an interesting history. The “Pie Jesu” is an ancient motet based on the last couplet of the “Dies Irae” (“Day of Wrath”) that was part of the old Latin Requiem Mass. The Vatican II liturgical reforms removed the “Dies Irae” from the Mass in order to emphasize Christian hope. A number of composers, among them Andrew Lloyd Webber – influenced by Gabriel Faure’s “Pie Jesu” – gave new musical expression to the prayer: “Kind/merciful Lord Jesus, grant them rest. Kind/merciful Lord Jesus, grant them rest eternal.” BTW, Faure’s Requiem includes the “Dies Irae” which has become part of the Good Friday period of meditation at Shepherd of the Hill, not because God is wrathful, but because we so often have reason to cry out “Libera Me!” from the depths of terror and desolation.