For your hardness of heart (pro thn sklhrokardian mwn). The word is apparently one of the few Biblical words (LXX and the N.T.). It is a heart dried up (sklhro), hard and tough. But from the beginning it hath not been so (ap arch de ouk gegonen outw). The present perfect active of ginomai to emphasize the permanence of the divine ideal. "The original ordinance has never been abrogated nor superseded, but continues in force" (Vincent). "How small the Pharisaic disputants must have felt in presence of such holy teaching, which soars above the partisan view of controversialists into the serene region of ideal, universal, eternal truth" (Bruce).