I do order and declare that all persons held as slaves [within the US] are, and henceforward shall be free; and that the Executive government of the United States, including the military and naval authorities thereof, will recognize and maintain the freedom of said persons.
King’s assessment of progress thereafter was stark: "One hundred years later, the life of the Negro is still sadly crippled by the manacles of segregation and the chains of discrimination…It is obvious today that America has defaulted on this promissory note insofar as her citizens of colour are concerned".
I think King was saying is that there must be an end to exceptionalism, the concept that one part of society stands elevated over others and is justified in using all means necessary to preserve that elevation. The context of "I have a Dream" was white exceptionalism (or supremacy). Now the West faces waves of Jihad based on fundamentalist Islamic exceptionalism and, as the exclusion of Pamela Geller and Robert Spencer from the UK shows, the Establishment will not even tolerate reference to the issue.
What will such denial of freedom produce for our generation: a Martin Luther King, or a Malcolm X?
"I have a Dream" speech on Youtube:
Text of the Emancipation Proclamation of 1863 - US Government Archives
Letter banning Pamela Geller from UK - Atlas Shrugs
Banning Geller and Spencer from UK will only increase grievance - Index on Censorship