The Vatican II document Gaudium et spes includes this packed summary of Trinitarian and anthropological self-gift: “the Lord Jesus, when he prays to the Father, ‘that all may be one . . . as we are one’ (Jn 17:21-22) and thus offers vistas closed to human reason, indicates a certain likeness between the union of the divine Persons and the union of God’s sons in truth and love. This likeness shows that man, who is the only creature on earth which God willed for itself, cannot fully find himself except through a sincere gift of self.”