Unfortunately, it was a lesson not learned frequently enough or soon enough to prevent the Holocaust. There are people who still can't see Pecola. Pecola the black girl. Pecola the Jew. All of the Pecolas.
Blacks are complicitous in our own suffering.
But there are those who use that fact to hide, to deny their own complicity. To deny their need to right wrongs that continue today. Even if, like Oscar Schindler, they didn't start or contribute to the problem. Oscar Schindler learned his lesson before it was too late. Later in the film, Schindler sees the girl in the red coat one more time.