Martin Luther King said this quote

We must accept finite disappointment but we must never lose infinite hope.

~ Martin Luther King

The ultimate measure of a man is not where he stands in moments of comfort and convenience but where he stands at times of challenge and controversy.

~ Martin Luther King

If a man hasn't discovered something that he will die for he isn't fit to live.

~ Martin Luther King

We must constantly build dykes of courage to hold back the flood of fear.

~ Martin Luther King