Edmund also easily fools Edgar, but not because of any misguided reliance upon astrological signs. Edgar's innate honesty and dignity make accepting Edmund's duplicity easy and prevents any questioning of Edmund's lies. Edgar cannot imagine that his brother would lie to him since Edgar would not lie to his brother. Edmund easily convinces Edgar that he should arm himself against their father, a man whom Edgar loves.
The double plot is an important literary device in this play. With two plots, perfectly intertwined and yet offering parallel lessons, Shakespeare is able to demonstrate the tragic consequences that result when man's law is given precedence over natural law. Eventually, Gloucester and Lear learn the importance of natural law when they recognize that they have violated these basic tenets, with both finally turning to nature to find answers for why their children have betrayed them. Their counterparts, Edmund, Goneril, Regan, and Cornwall, represent the evil that functions in violation of natural law.
The double plot serves an important function, emphasizing natural law as an essential facet of both plots. Shakespeare then uses the two plots to point to how essential an acknowledgment of natural law is in a moral society. In both plots the absence of natural law is destructive, and ultimately even those who are good cannot act to save Cordelia or the other good characters from the ravages of evil and tyranny.
