The Apostles faced up to the problem of Judas/ They seem to have been convinced that their number should be twelve and so selected Matthias by lot. He had been one of the many who had literally followed Jesus when he tramped around teaching in Synagogues and curing the sick in body and in mind. It was from these people that the initial conversions were made. Being one of the Twelve was also seen to be an office holder and recipient of a special grace from Jesus. This grace specifically given to the original twelve, even to Judas, became in  time the priesthood as specifically witnessed in the  Apostolic Foundations of the Middle-East and Rome. 

Dear Lord may your Grace again fill the hearts of your faithful and their ministers so that we may be guarded against all temptations and be secure in the knowledge that our Apostolic Foundation is indeed  directly from you.

Jesus passes  on to us the Love that fills the Trinity of God ; he is one with the Father and the Holy Spirit, This teaching is certainly no human thinking but a Truth that Jesus has been willed by the Father to reveal. His witness of this Truth takes place in Jerusalem and  where today the fighting continues is the place that the  words of God " What I command you is to love one another" were spoken by Our Lord who was there Crucified and Risen to Glory. 

Dear Lord you assure us that what we ask for in your name will be given by the Father, let the people who today are preparing to kill one another just stop and remember the holiness of their native land.