Chapter XXXIV.—System of Marcus; A Mere Impostor; His Wicked Devices Upon the Eucharistic Cup.
A certain other teacher among them, Marcus, an adept in sorcery, carrying on operations partly by sleight of hand and partly by demons, deceived many from time to time. This (heretic) alleged that there resided in him the mightiest power from invisible and unnameable places. And very often, taking the Cup, as if offering up the Eucharistic prayer, and prolonging to a greater length than usual the word of invocation, he would cause the appearance of a purple, and sometimes of a red mixture, so that his dupes imagined that a certain Grace descended and communicated to the potion a blood-red potency. The knave, however, at that time succeeded in escaping detection from many; but now, being convicted (of the imposture), he will be forced to desist from it. For, infusing secretly into the mixture some drug that possessed the power of imparting such a colour (as that alluded to above), uttering for a considerable time nonsensical expressions, he was in the habit of waiting, (in expectation) that the (drug), obtaining a supply of moisture, might be dissolved, and, being intermingled with the potion, might impart its colour to it. The drugs, however, that possess the quality of furnishing this effect we have previously mentioned in the book on magicians. And here we have taken occasion to explain how they make dupes of many, and thoroughly ruin them. And if it should prove agreeable to them to apply their attention with greater accuracy to the statement made by us, they will become aware of the deceit of Marcus.
Reproduced in full. Translation: Ante-Nicene Fathers, vol. 5 (Roberts and Donaldson, 1886), public domain (Public domain).