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.

Martin Luther King, Jr. (1929–1968) American clergyman, civil rights leader, social activist, preacher

Letter from Birmingham Jail (16 Apr 1963)
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Another phrase King used on repeated occasions, e.g., "Injustice anywhere is a threat to justice everywhere. Therefore, no American can afford to be apathetic about the problem of racial justice. It is a problem that meets every man at his front door" -- "The Rising Tide of Racial Consciousness," Speech, National Urban League, New York (6 Sep 1960).