He was never bitter. Read his July.4h, 1852 Address, he defends the Decleration and the Constitution as wonderful Freedom documents, and call the nation to live up to them.
It is my understanding that he was bitter, until Lincoln challenged him to read the Constitution and Bill of Rights for himself and not just rely upon what he was told about it.
This was his speech in 1852.
In 1852, he delivered another of his more famous speeches, one that later came to be called “What to a slave is the 4th of July?”
In one section of the speech, Douglass noted, “What, to the American slave, is your 4th of July? I answer: a day that reveals to him, more than all other days in the year, the gross injustice and cruelty to which he is the constant victim. To him, your celebration is a sham; your boasted liberty, an unholy license; your national greatness, swelling vanity; your sounds of rejoicing are empty and heartless; your denunciations of tyrants, brass fronted impudence; your shouts of liberty and equality, hollow mockery; your prayers and hymns, your sermons and thanksgivings, with all your religious parade, and solemnity, are, to him, mere bombast, fraud, deception, impiety, and hypocrisy—a thin veil to cover up crimes which would disgrace a nation of savages.”
That sounds bitter to me. But it changed when he was challenged by Lincoln to read the Constitution and Bill of Rights. When he did that, that’s when he advocated for America to be for all people.
I have read the address! It's a fantastic oratory.(Notwithstanding my straightforward presentation) At this point its up to nearly 200,000 views. (FWIW, not my personal YouTube channel)
https://www.youtube.com/watch?v=4NNBIMYGtLo
Douglass also eagerly debated the Constitution itself with many people, arguing that the Constitution is anti-slavery, and tore to pieces arguments we deal with today about the 3/5ths clause and many other aspects. (FWIW, this is my YouTube page)
The American Constitution and the Slave - Is the Constitution pro-slavery or anti-slavery?
https://www.youtube.com/watch?v=PbJ5WdKpMro
Many on the left try to claim Frederick Douglass as their own. In the details, there's not a shred of Douglass they could claim.
Let us not forget that Frederick Douglass was a Preacher. That's how he got so good at speaking. He did so every Sunday morning speaking about The Lord.
Not sure if that is true, but it was certainly not made a prominent feature of his life.
Read his July.4h, 1852 Address, he defends the Decleration and the Constitution as wonderful Freedom documents, and call the nation to live up to them.
Agree with you here.