The twin sisters Agnes Lewis (1843–1926) and Margaret Gibson (1843–1920) were pioneering biblical scholars who became experts in a number of ancient languages. Travelling widely in the Middle East, they made several significant discoveries, including one of the earliest manuscripts of the four gospels in Syriac, the language believed to have been spoken by Jesus himself. Previously published as part of the Horae Semitica series, this first fascicule contains the third-century Syriac text of the Didascalia Apostolorum, edited by Gibson. Traditionally attributed to the apostles, the text is a treatise on Church law and doctrine, covering topics including church organisation, charity and forgiveness. Gibson described it as a 'potent instrument' used to gain the 'unquestioning obedience of the Christian people'. An important resource for the Syriac scholar, the edition also includes additional material from a variety of sources, and is of considerable significance to ecclesiastical history.