The Emancipation Proclamation: Annotated

'Abraham Lincoln proclaimed freedom for enslaved people in America on January 1, 1863. Today, we’ve annotated the Emancipation Proclamation for readers.'

At JSTOR.

"In this second document in our Annotations series, we’ve collected scholarship around Lincoln’s progress toward issuing the Proclamation (including his deliberations between decision and Proclamation), his concerns about the Constitutionality of, and possible challenges to it, the responses of Americans to the decree, and how views of Lincoln held by lay people (and historians) have changed through time."

See Lincoln, "The Gettysburg Address", Gateway to the Great Books (10 Vol., 1963) volume 6;
We Hold These Truths: Understanding the Ideas and Ideals of the Constitution, by Mortimer J. Adler, p. 194.