It is important to note that Willy uses the past to attempt to create order in a present that is no longer bearable. However, Willy selectively chooses and arranges his memories and facts in a way that is pleasing to him. He does not randomly choose memories, nor does he allow himself to remember everything. Instead he tries to carefully edit out anything that could disrupt the order he desires. The conversation between Bernard and Willy is unsettling to Willy because it awakens unbidden memories that he prefers to deny.
Up until this point, Willy blames Biff's failures on laziness and lack of motivation, but after Howard fires him, Willy begins to consider that perhaps he is responsible in some way: "It keeps going around in my mind, maybe I did something to him. I got nothing to give him." Willy has muddled this idea around but has not thought of what he might have done wrong. Bernard suggests that something else is behind Biff's downward spiral since high school, and he hints that Willy is connected to the change in Biff. Once Bernard connects the change in Biff to Biff's Boston visit, Willy knows what he did wrong. He becomes defensive toward Bernard as a way of denying his own culpability. He refuses to admit anything to Bernard, but Willy suspects that he has not only ruined his own life, but his son's as well.
