{Lest haply they should turn again, and it should be
forgiven them} (m(8870)ote epistreps(9373)in kai apheth(8869) autois). Luke
does not have these difficult words that seem in Isaiah to have
an ironical turn, though  Mt 13:15  does retain them even after
using hoti for the first part of the quotation. There is no way
to make m(8870)ote in  Mr 4:12  and  Mt 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.