As soon as he had taken his seat, filled with hope and admiration, I rose, and declared that PATRICK HENRY, of revolutionary fame, never made a speech more eloquent in the cause of liberty, than the one we had just listened to from the lips of that hunted fugitive. So I believed at that time--such is my belief now. I reminded the audience of the peril which surrounded this self-emancipated young man at the North,--even in Massachusetts, on the soil of the Pilgrim Fathers, among the descendants of revolutionary sires; and I appealed to them, whether they would ever allow him to be carried back into slavery,--law or no law, constitution or no constitution. (Preface.4)
Garrison is talking about a speech Douglass gave to an audience of abolitionists in the North, some time after he was free. So when he compares Douglass to Patrick Henry, he wants to remind the audience that Douglass didn't just get his freedom, he had to fight for it. (Patrick Henry, remember, is famous for saying "Give me liberty or give me death.")
But there's more to it than that. When he starts talking about "the peril which surrounded this self-emancipated young man at the North," he wants to remind us that the danger isn't over for Douglass. Even in the North, where he was free, Douglass could still be kidnapped by his former owners and taken back to the South to be a slave again. For Garrison, the fact that Douglass can't be safe even there in Massachusetts, where the Pilgrims landed and the Revolutionary War began, shows that slavery needs to abolished everywhere.
Letter from Wendell Phillips
They say the fathers, in 1776, signed the Declaration of Independence with the halter about their necks. You, too, publish your declaration of freedom with danger compassing you around. In all the broad lands which the Constitution of the United States overshadows, there is no single spot,--however narrow or desolate,--where a fugitive slave can plant himself and say, "I am safe." (letter.7)
In his letter to Douglass, Wendell Phillips reminds us that even once he was free, Douglass ran a big risk in writing his story: at any time, he could be kidnapped and taken back down South and enslaved. And even though Phillips compares Douglass to the founding fathers (and he compares Douglass's book to the Declaration of Independence), he points out that the American freedom that the Declaration asserted doesn't do much good for a slave like Douglass.
William Lloyd Garrison
"No Compromise With Slavery! No Union With Slaveholders!" (Preface.13)
William Garrison's preface to Douglass's book ends with this slogan. Though he is trying to stir people up, it's more than just a call to arms. Abolitionists in those days agreed that slavery was a bad thing, but they didn't always agree on what should be done about it. And while Douglass was always interested in the promise of the United States, the land of the free, Garrison was a radical abolitionist who believed that it was better to break away from the United States than share in the sin of slavery. So when he says that there should be "No Union With Slaveholders," he's saying it would be better for the northern states to secede rather than to remain part of a "union" with slave states. Not all abolitionists agreed with this, but Garrison was convinced that it was a sin to compromise with slavery at all.
What Douglass thinks is harder to say; Garrison was his friend and mentor when he wrote the Narrative, but they would have a falling out over the issue in later years. Ironically, it would be the slave states that seceded from the union, which is why Abraham Lincoln fought the Civil War, to defend the union – and why the northern troops were called the "Union" army. But in the 1840s, it was the reverse: only radical abolitionists like Garrison talked about secession.
A representative could not be prouder of his election to a seat in the American Congress than a slave on one of the out-farms would be of his election to do errands at the Great House Farm. (2.7)
Being selected to work in the Great House Farm instead of the fields was seen to be a great honor for a slave, but Douglass is being ironic here. After all, even a slave in the Great House is still a slave. And even though America is a country where almost anyone could grow up to be president, the highest honor a slave could ever hope to attain is to be a servant in a slightly nicer part of the plantation.
William Lloyd Garrison
In coming to a fixed determination to run away, we did more than Patrick Henry, when he resolved upon liberty or death. With us it was a doubtful liberty at most, and almost certain death if we failed. For my part, I should prefer death to hopeless bondage. (10.26)
Remember Patrick Henry? He was famous for saying "Give me liberty or give me death" during the Revolutionary War. In the preface, Garrison already compared Douglass to Patrick Henry, but when Douglass brings up the reference he's saying that he and his slave friends are even braver than one of the fathers of the country.