What does wiesel mean by saying that "if we forget, we are accomplices"?

Elie Wiesel was a Nobel Peace Prize winner in 1986. Wiesel was an American-Jew who survived of the Nazi genocide in World War II. He wrote about his and other Jewish's people's experiences of suffering during the Holocaust.  

The quote ""if we forget, we are accomplices" is from Wiesel's Noble Prize of Peace award acceptance speech. The quote means that staying neutral, silent and not taking action in the face of oppression or suffering imposed by others, we are basically accomplices, making our suffering endure.