It is the mark of an educated mind to be able to entertain a thought without accepting it.
---Aristotle (384 BC - 322 BC)

Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity.
---Martin Luther King Jr., Strength to Love, 1963

Freedom is never voluntarily given by the oppressor; it must be demanded by the oppressed.
---Martin Luther King Jr. (1929 - 1968), Why We Can't Wait

Nobody can give you freedom. Nobody can give you equality or justice or anything. If you're a man, you take it.
---Malcolm X (1925 - 1965), Malcolm X Speaks, 1965

We hate some persons because we do not know them; and we will not know them because we hate them.
---Charles Caleb Colton (1780 - 1832)

In the end, we will remember not the words of our enemies, but the silence of our friends.
---Martin Luther King Jr. (1929 - 1968)

I am free of all prejudice. I hate everyone equally.
---W. C. Fields (1880 - 1946)

(These quotes are taken from http://www.quotationspage.com) 

external links:

Adam Clayton Powell Jr. & Dr. Martin Luther King Jr