Injustice anywhere is a threat to justice everywhere.
 Martin Luther King, Jr., Letter from a Birmingham Jail (16 April 1963). copy citation

Context

“Like Paul, I must constantly respond to the Macedonian call for aid. Moreover, I am cognizant of the interrelatedness of all communities and states. I cannot sit idly by in Atlanta and not be concerned about what happens in Birmingham. Injustice anywhere is a threat to justice everywhere. We are caught in an inescapable network of mutuality, tied in a single garment of destiny. Whatever affects one directly, affects all indirectly. Never again can we afford to live with the narrow, provincial "outside agitator"” source