Firmilian of Caesarea, Letter to Cyprian 1
Firmilianus greets his brother Cyprian in the Lord. We have received the letters you sent us through our most beloved deacon Rogatianus, and we have given the greatest thanks to the Lord because, though we are separated in body, we have been united in spirit, as if we shared not merely one region but inhabited the very same house at the same time. That is fitting to say, because the spiritual house of God is one. For in the last days, says the Prophet, the mountain of the Lord and the house of God will be manifest above the tops of the mountains (Isaiah 2:2-3). Into it they are gathered with joy, just as this Psalm asks of the Lord, to inhabit the house of God through all the days of life (Psalm 133:1). So also in another place it has been made manifest that there is among the saints a great charity of will to come together as one. Behold, how good and pleasant it is for brothers to dwell in unity (Psalm 133:1).
Latin
Firmilianus Cypriano fratri, in Domino salutem. Accepimus per Rogatianum charissimum nostrum diaconum a vobis missum litteras quas ad nos fecisti, frater dilectissime; et gratias propter hoc Domino maximas egimus quod contigerit ut qui corpore ab invicem separamur sic spiritu adunemur quasi non unam tantum regionem tenentes, sed in ipsa atque in eadem domo simul inhabitantes. Quod et decet dicere, quia et spiritalis domus Dei una est. Erit enim in novissimis, ait Propheta, diebus manifestus mons Domini et domus Dei super vertices montium. In quam convenientes cum jucunditate adunantur, secundum quod et in Psalmo hoc postulatur a Domino inhabitare in domo Dei per omnes dies vitae. Unde et in alio loco manifestatum est esse apud sanctos magnam voluntatis charitatem inunum convenire. Ecce, inquit, quam bonum et voluptabile est ut habitent fratres in unum!