" The idea behind verses about the sealing of hearts appears to be the psychological law that if a person once does a good or an evil deed, his chances of repeating that kind of action increase and of doing its opposite proportionately decrease. With constant repetition of an evil or of a good action, it becomes almost impossible for a person to do the opposite, or even to think of it, so much so that while men's hearts become " sealed" and their eyes " blinded" if they do evil, their doing good produces such a state of mind that the devil himself can have no sway over it. Nevertheless, actions which create a psychological habit, however strong their influence may be, must not be construed as absolute determinants, for there is no " point of no return" for human behavior: genuine repentance (tauba) can turn an apparently wholly evil man into a paragon of virtue; on the other hand, although this is much more rare, an apparent paragon of virtue (even a prophet!) can turn into a near devil enmeshed in carnal pleasures . "