On the Unity of the Catholic Church 9

For this reason the Holy Spirit also came in a dove. It is a simple and joyful creature, not bitter with gall, not savage with bites, not violent with tearing claws; it loves human dwellings, knows the fellowship of one home; when they breed they bring forth their young together; when they fly about they keep close to one another; they spend their life in common intercourse; they acknowledge the concord of peace with the kiss of the beak; they fulfil the law of unanimity in all things. This is the simplicity that should be known in the church; this is the charity to be attained, that the love of the brotherhood may imitate the doves, that gentleness and mildness may equal the lambs and sheep. What are the ferocity of wolves, the madness of dogs, the deadly poison of serpents, and the bloody savagery of beasts doing in a Christian breast? We must rejoice when such people are separated from the church, lest they prey upon the doves and sheep of Christ with their savage and poisonous contagion. Bitterness cannot cohere and be joined with sweetness, darkness with light, rain with fair weather, war with peace, barrenness with fruitfulness, drought with springs, storm with calm. Let no one think that the good can depart from the church: the wind does not carry away the wheat, nor does the storm overturn the tree founded on a solid root. It is the empty chaff that is tossed by the tempest; it is the weak trees that are overturned by the onset of the whirlwind. These the apostle John curses and strikes, saying: "They went out from us, but they were not of us. For if they had been of us, they would have remained with us."