"But what is the nature and meaning of this unity? It is deeper than convenience, organisation, human brotherhood. It is less formally expounded than tacitly assumed. There is no Christian community mentioned in the New Testament which has not behind it some authority responsible to a larger whole, and there is no letter in the New Testament (except the epistle to Philemon} which does not show that the local society owes obedience to someone who addresses it it in the name of the larger whole.Michael Ramsey: The Gospel and the Catholic Church (1936)
Not of convenience alone, this unity is connected with the truth about Christ himself. It is the unity of His own Body, springing from the unity of God, uttered in the passion of Jesus, and expressed in an order and a structure...."