Between Adomnán’s Vita Columbae and Bede’s account in his Historia ecclesiastica, Saint Columba’s life and missionary career are the best recorded of all early Irish ecclesiastics. Further, and in great contrast to his 5th-century British missionary predecessor, Saint Patrick, Columba’s chronology has not been the subject of controversy in modern times. At least from the 17th-century scholarship has been almost unanimous that Columba died in AD 597, a date that derives from Adomnan’s assertion that he died on Sunday, and that he left Ireland in AD 563, which likewise derives from Adomnán’s statement that his mission had lasted 34 years. However, Dáibhí Ó Cróinin’s identification in 1985 that Padua, Biblioteca Antoniana, I 27, 76r-77v preserves a copy of the paschal table followed by the early Irish church demonstrated that the feria of the kalends of January was the primary chronological criterion used by early insular Christian scholars to identify each successive year. It was this discovery that prompted examination of the ferial data preserved in the Clonmacnoise group of Irish annals, which in turn revealed that annals were compiled contemporaneously with Columba’s life, and hence that the annalistic account of Columba predates those of Adomnán and Bede by a century. These ferial data locate Columba’s obit unmistakeably at AD 593, and this four-year discrepancy raises serious doubt regarding the veracity and honesty of Adomnán’s account of Columba’s life.