Variations among MSS are sometimes due to scribes having misheard a word being dictated or through some other human error. But also sometimes alterations were made for doctrinal reasons. For example a reading loutron = purification in Mark 10: 45 may have been changed from lutron = ransom to make the verse conform to the theology of Heb. 9: 14. Cf. also textual variants at Rev. 1: 5. Sometimes it seems that a scribe was motivated to ensure that his text did not imply an unacceptable doctrine; e.g. Luke 2: 22: ‘the time for their purification’ has been altered to ‘her purification’ in certain Syriac and Coptic MSS in the interests of the doctrine of the Virgin Birth and as a correction because the rite of purification involved the mother alone anyway (Lev. 12: 4–6). Similarly, several MSS (e.g. D, Codex Bezae, c. 400 CE) omit Mark's mistaken ‘when Abiathar was high priest’ (2: 26).