Today's selection comes from Martin Luther King Jr. 

I call on the young men of America who must make a choice today to take a stand on this issue. Tomorrow may be too late. The book may close. And don't let anybody make you think that God chose America as his divine, messianic force to be a sort of policeman of the whole world. God has a way of standing before the nations with judgment, and it seems that I can hear God saying to America, "You're too arrogant! And if you don't change your ways, I will rise up and break the backbone of your power, and I'll place it in the hands of a nation that doesn't even know my name. Be still and know that I'm God."

This is part of a speech he gave at Ebenezer Baptist Church in 1967.  When I first came across this speech I was pretty surprised.  He is clearing referencing Vietnam and how the US will lose that war.  They don't teach you this speech at school.  When you are taught about Martin Luther King Jr. it centers around the "I Have A Dream" speech.  It is important to keep in mind he fought for a variety of issues throughout his life.