The left eye delved narrowly into the past while the right gazed wide and affrighted into a future of blackness, error, and ruin. And he was suspended between radiance and darkness. Between bitter irony and faith. Sharply he turned away. (3.4.16)
Biff's ending epiphany is a departure from the style of the rest of the novel, but it's a great note on which to end the novel. These characters are all caught between beauty and despair. Some of them survive, some of them don't.