In the said VERSE (NO.7) and several other verses, losing the power of distinction and comprehension is notified by setting a seal upon the hearts. When usually people put something in a pocket or sack, they plumb it and seal it, for wanting not to be opened or touched. In Arabic language, such a plumb or seal is called `KHATM'. This is a simile of the obstinate rejectors of faith, that due to continuous sinning, their minds are closed to advices and sealed and their hearts are plumbed so that no truthful words can penetrate in them. Man should therefore be careful about himself, when even he does something wrong. He should wash out the wrong or the fault, what ever it is; with the clean water of repentance, and doing good deeds for amendment.