What is the catharsis in Death of a Salesman?

In Arthur Miller's play, Death of a
Salesman, Willy Loman, the main character, has for years been living among
the illusions of the past. He thinks the world should be as it was, never changing as,
for instance, his job and the market place in which he works,
changes.

Willy remembers with regret that his brother Ben
had encouraged him to go to Africa to become rich, and he has dialogues with Ben all the
time, though Ben is dead through flashbacks, but unfortunately, this is where Willy
spend a lot of time.

Willy has two sons. His oldest is
Biff. When Biff was in high school, he was the star football player, with a scholarship
to college. However, at the end of his senior year, Biff fails math and does not
graduate. All of his prospects disappear. However, for Willy, Biff is still this man who
is well-liked and can do anything. He imagines that Biff can get any job he wants, and
that other people see Biff as Willy imagines him to
be.

Near the end of the play, Biff has been trying to do
what his father asks: go to an old boss and ask for a job. Biff's life is nothing like
Willy imagines it, but Willy will never listen when Biff tries over and over to explain.
Finally, unsuccessful to even get in to see his old boss, Biff
snaps and tells his father how things truly are in his life, and that he is not the man
his father believes him to be. He insists that there are no bad feelings on his part for
his father, but begs Willy to see him as he really is; he sobs holding onto his
father.

This catharsis removes an enormous weight from
Biff's shoulders so he can stop trying to be what his dad wants him to be, and simply be
Biff, which is a hard job for him in itself. Willy is touched by Biff's behavior and
realizes that his son loves him. This is an awe-inspiring moment for him. But the
illusion seems to linger: Willy still believes that his son is going to be a great
success.

Instability has been growing in Willy throughout
the play. And even it appears that he reconnects with Biff, Willy loses the battle to
keep his "head above water" in terms of the sorrows and disappointments that weigh him
down, and he takes his own life. Biff argues at the funeral that Willy was trying
desperately to find out who he was.

The catharsis has
allowed Biff to begin to move forward, stating the he knows who he
is. While Willy's death is tragic, we see that perhaps Biff will finally be able to turn
himself around and experience the satisfaction Willy could never connect
with.