The Prescription Against Heretics 31
31 Truth First, Falsehood Afterwards, as Its Perversion. Christ's Parable Puts the Sowing of the Good Seed Before the Useless Tares PL 2, 44
Let me return, however, from this digression to discuss the priority of truth, and the comparative lateness of falsehood, deriving support for my argument even from that parable which puts in the first place the sowing by the Lord of the good seed of the wheat, but introduces at a later stage the adulteration of the crop by its enemy the devil with the useless weed of the wild oats. For herein is figuratively described the difference of doctrines, since in other passages also the word of God is likened unto seed. From the actual order, therefore, it becomes clear, that that which was first delivered is of the Lord and is true, whilst that is strange and false which was afterwards introduced. This sentence will keep its ground in opposition to all later heresies, which have no consistent quality of kindred knowledge inherent in them—to claim the truth as on their side.
Id itaque esse verum et dominicum, quod prius sit traditum; falsum, quod posterius.
Sed ab excessu revertar ad principalitatem veritatis, et posteritatem mendacitatis disputandam, ex illius quoque parabolae patrocinio, quae bonum semen frumenti a Domino seminatum in primore constituit, avenarum autem sterilis foeni adulterium ab inimico diabolo postea superducit. Proprie enim doctrinarum distinctionem figurat, quia et alibi verbum Dei seminis similitudo est. Ita ex ipso ordine manifestatur, id esse dominicum et verum, quod sit prius traditum; id autem extraneum et falsum, quod sit posterius immissum. Ea sententia manebit adversus posteriores quasque haereses, quibus nulla constantia de conscientia competit ad defendendam sibi veritatem.