Cosmas the Monk (fl. 7th c) was a monk from Sicily (hence also known as Cosmas the Sicilian[1]), best known as the tutor of John of Damascus[2] and Cosmas of Maiuma.[3]
Any knowledge of Cosmas comes from the notably unreliable[4] tenth-century hagiography of John of Damascus. Apparently, John's father met Cosmas, a Sicilian who knew Greek, on the shores of Italy when the latter was about to be executed.[1] He was crying loudly and when asked why a monk would cry in the face of death, answered that he was bemoaning the loss of the knowledge he had gathered, "for he knew nearly everything under the sun." In response, John's father (a judge) had him released and appointed him as tutor for his son.[5]