Pope Benedict XVI: The Pieta completes the picture of the Cross

From Pope Benedict XVI, then Joseph Cardinal Ratzinger, in Mary:  The Church at the Source by Joseph Cardinal Ratzinger and Hans Urs von Balthasar, translated by Adrian Walker :

Michelangelo's Pieta

The Pieta completes the picture of the Cross, because Mary is the accepted Cross, the Cross communicating itself in love, the Cross that now allows us to experience in her compassion the compassion of God.  In this way the Mother's affliction is Easter affliction, which already inaugurates the transformation of death into redemptive being-with of love.  Only apparently have we distanced ourselves from the "rejoice" with which the narrative of Mary begins.  For the joy announced to her is not the banal joy clung to in forgetfulness of the abysses of our being and so condemned to plunge into the void.  It is the real joy that gives us courage to venture the exodus of love that pain does not destroy but first brings to its maturity.  Only the joy that stands the test of pain and is stronger than affliction is authentic.