This too has been often proved by many experiments; viz., that those who entered the bonds of friendship from a beginning of conspiracy, cannot possibly preserve their harmony unbroken; either because they tried to keep it not out of their desire for perfection nor because of the sway of Apostolic love, but out of earthly love, and because of their wants and the bonds of their agreement; or else because that most crafty foe of ours hurries them on the more speedily to break the chains of their friendship in order that he may make them breakers of their oath. This opinion then of the most prudent men is most certainly established; viz., that true harmony and undivided union can only exist among those whose life is pure, and who are men of the same goodness and purpose.
Thus much the blessed Joseph discoursed in his spiritual talk on friendship, and fired us with a more ardent desire to preserve the love of our fellowship as a lasting one.
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 2, vol. 11 (Schaff and Wace, 1894), public domain (Public domain).