Although scholars have often made inferences about the Greek texts that lay behind the Old Syriac and Peshitta versions of the Gospels, very few have ever attempted to formulate systematic rules for such inferences. This volume investigates a wide range of textual phenomena and formulates clear and simple rules for the use of Syriac texts as witnesses to the underlying Greek. It becomes possible to uncover errors that have accumulated during the evolution of the Greek New Testament textual apparatus. Williams argues these errors generally stem from the unjustified use of Syriac witnesses.