Save Mankind

O King of the Nations, and their Desire, the Corner-stone, who makest both one:
come and save mankind, whom thou formedst of clay.
Divine Worship: The Missal

‘The antiphon speaks of the Son as having already effected the gathering (“of the mighty arch of man” would read, in a literal translation, “who make the two one,” an allusion to Ephesians 2.14). The Church begs him to come and save man, whom God has fashioned in his own image but whose features sin has distorted. We await the return of Christ, who is the Keystone, or, in a somewhat different image, the Cornerstone upon which the Church, as the definitive ingathering of mankind, is built’. 

from The Liturgical Year, 1977, by Adrien Nocent OSB, 1913-1996