From the Retractations, Book II. Chap. 60. "Then also I wrote a Book against Lying, the occasion of which work was this. In order to discover the Priscillianist heretics, who think it right to conceal their heresy not only by denial and lies, but even by perjury, it seemed to certain Catholics that they ought to pretend themselves Priscillianists, in order that they might penetrate their lurking places. In prohibition of which thing, I composed...