As in the post below, Douglass' speeches are fascinating but they make me aware of all I don't know about abolitionism and the pre-war period. In Douglass' speech The Dred Scott Decision we learn that he and his mentor William Lloyd Garrison, publisher of The Liberator, ultimately disagreed about whether the Union should be preserved and whether the Constitution was ultimately a document supporting slavery or a tool for ending it. These are deep philosophical questions that I would love to delve into more deeply.
On the Library's periodical database Ebsco Host I uncovered an article that might help:
If you click this link, you will be prompted to enter your library card number to access the article. (and for what it's worth, ATQ stands for American Transcendental Quarterly)