Last fall, Adam posted a quotation from Pseudo-Dionysius’s Letter 6, “To Sosipater, Against Polemics” (did you find that by way of Prof. Rorem?); Maggi Dawn posted the same quotation (here, from the CCEL’s text version; the conversion of Pseudo-Dionysius’s Works seems not to have reached the “Letters” part of the volume):
LETTER VI. To Sopatros, Priest.
Do not imagine this a victory, holy Sopatros, to have denounced a devotion, or an opinion, which apparently is not good. For neither — even if you should have convicted it accurately — are the (teachings) of Sopatros consequently good. For it is possible, both that you and others, whilst occupied in many things that are false and apparent, should overlook the true, which is One and hidden. For neither, if anything is not red, is it therefore white, nor if something is not a horse, is it necessarily a man. But thus will you do, if you follow my advice, you will cease indeed to speak against others, but will so speak on behalf of truth, that every thing said is altogether unquestionable.
Well said, Denys.