The same year as Douglass autobiography, Whitman published by Blue Ontario's shores. For those who took Epic in year 1, you'll recognize that this poem locates itself as an epic in the shape of Milton's Paradise Lost and Wordsworth's The Prelude. But unlike Milton or Wordsworth, who respectively see the Divine and Nature, as their modern muse, Whitman claims Democracy as his inspiration, and furthermore, Whitman dedicates the purpose of poetry andbieng a poet, as chanting the grace of the "great idea" of Democracy. 

Since Whitman never actually saw the Ontario or Rochester, it's hard not to read this as a backward glance and justification for aboliiton. The poem is relatively long, but one passage reads as such:

For the great Idea, the idea of perfect and free individuals,
For that idea the bard walks in advance, leader of leaders,
The attitude of him cheers up slaves and horrifies foreign despots. 

Without extinction is Liberty! without retrograde is Equality!
They live in the feelings of young men, and the best women;
Not for nothing have the indomitable heads of the earth been always ready to fall for Liberty.

11

For the great Idea!
That, O my brethren—that is the mission of Poets. 

[…]

I swear I dare not shirk any part of myself,
Not any part of America, good or bad,
Not the promulgation of Liberty—not to cheer up slaves and horrify foreign despots,
Not to build for that which builds for mankind,
Not to balance ranks, complexions, creeds, and the sexes,
Not to justify science, nor the march of equality,
Nor to feed the arrogant blood of the brawn beloved of time.

I swear I am for those that have never been master’d!
For men and women whose tempers have never been master’d, 
For those whom laws, theories, conventions, can never master.

I swear I am for those who walk abreast with the whole earth!
Who inaugurate one, to inaugurate all.