9وَجَعَلنا مِن بَينِ أَيديهِم سَدًّا وَمِن خَلفِهِم سَدًّا فَأَغشَيناهُم فَهُم لا يُبصِرونَAli UnalAnd We have set a barrier before them and a barrier behind them, and (thus) We have covered them (from all sides), so that they cannot see.1The comparison here symbolizes the condition in which stubborn unbelievers finds themselves. As they are too arrogant to reflect on their existence in an unprejudiced way; so, too, they fail to observe the universe around them in any way that is beneficial. They are, as if in veils of darkness, blind to their environment which is full of signs pointing to God’s Existence and Oneness. Their blindness comes from arrogance and the fact that their hearts are so dead that they have lost the ability to believe. So, even if they study “nature” and are specialists in many sciences, this information increases them only in ignorance about God and the ultimate truth on which the universe is based.