It has long been a practice for monks to copy apophthegmatic texts attributed to various earlier patristic authors. One such manuscript, found in the Vatican library contains sayings attributed to Isaac the Syrian (i.e. Isaac of Nineveh). In this article, Marius Besson presents the text of this manuscript along with a brief introduction. Besson finds a large portion of the same text in another manuscript, but only the more complete Vatican manuscript includes the attribution to Isaac. Besson concludes that the two manuscripts have separate transmission histories and observes that one was freely adapted by the copyists. While Besson clearly doubts the authenticity of the claim concerning authorship, he does not delve deeply into such historical questions. However, Besson does note that this text has important historical implications because it has parallels in various other early Christian documents, most notably the usage of the “two ways” metaphor for Christianity. Besson presents the Greek text of the two collated manuscripts with variant readings in an apparatus and even includes a separate apparatus for the parallel texts in the Apostolic Constitutions, the Didache, the Epistle of Barnabas, the Doctrine of the Twelve Apostles, and the Ecclesiastical Canons of the Apostles.