In this historic first attempt to catalogue systematically the Syriac witnesses to the Greek New Testament, Gwilliam organizes the authorities that set the text of the Peshitto New Testament. Among these ancient witnesses are examples of what Gwilliam cites as Syriac Massorah, early attempts to preserve the original orthography and pronunciation of the Syriac texts. Arabic and Persian versions are also considered. Eastern and Western types of texts are compared, and various readings are provided as illustrative examples. Gwilliam also addresses revisions of the Peshitto New Testament in the Syrian Church and guidelines for how existing material might be used for a critical edition of the Peshitto.

George Henry Gwilliam, Fellow of Hertford College and editor of the influential Oxford Peshito, was a noted champion of the importance of Syriac for understanding the textual criticism of the New Testament. Along with P. E. Pusey, Gwilliam published a standard-setting critical edition of the Peshitta.