Lest haply they should turn again, and it should be forgiven them (mhpote epistrepswsin kai apeqh autoi). Luke does not have these difficult words that seem in Isaiah to have an ironical turn, though Matthew 13:15 does retain them even after using oti for the first part of the quotation. There is no way to make mhpote in Mark 4:12 and Matthew 13:15 have a causal sense. It is the purpose of condemnation for wilful blindness and rejection such as suits the Pharisees after their blasphemous accusation against Jesus. Bengel says: iam ante non videbant, nunc accedit iudicium divinum. Jesus is pronouncing their doom in the language of Isaiah. It sounds like the dirge of the damned.