Until that year, day, hour, arrive, With head, and heart, and hand I’ll strive, To break the rod, and rend the gyve, The spoiler of his prey deprive- So witness Heaven! And never from my chosen post, Whate’er the peril or the cost, Be driven.
Douglass returns to his previous practice of rhyming for this entire conclusion, truly giving the audience his thesis in a way that sticks in their minds more than the rest of his speech would.
I have detained my audience entirely too long already. At some future period I will gladly avail myself of an opportunity to give this subject a full and fair discussion.
The keyword to me here is "my audience." Douglass has detained his audience for entirely too long, not because his speech was needlessly long, but rather due to the fact that his audience likely can't bring themselves to care for this period of time. He then clarifies this distinction in the next sentence by claiming that he was in fact too short in his speech then he should be in adequately expressing his arguments on slavery.
The sin of which it is guilty is one of omission as well as of commission.
Using omission and commission as critiques on the church is not only fitting given the context, but also sticks in the audiences mind longer than other parts of the speech based on it's rhyme.
In glaring violation of justice, in shameless disregard of the forms of administering law, in cunning arrangement to entrap the defenseless, and in diabolical intent, this Fugitive Slave Law stands alone in the annals of tyrannical legislation.
Here, Douglass personifies the slave trade as a criminal who abuses the defenseless and takes pleasure in the suffering of his victims. This is in no way a falsehood, but likely a reflection that his audience was unaware of, or at least not seen presented so well. In doing so, along with his large introduction that eased the audience into his speech, Douglass once again demonstrates his talent for persuasive rhetoric.
Friends and citizens, I need not enter further into the causes which led to this anniversary. Many of you understand them better than I do. You could instruct me in regard to them. That is a branch of knowledge in which you feel, perhaps, a much deeper interest than your speaker.
Here, Douglass stokes the egos of his listeners without hiding who he is. Saying that his listeners are smart enough to instruct him appeals to their sense of superiority, yet doesn't downplay his own intelligence by making it clear that this gap of knowledge isn't due to ability, but rather interest.
Citizens, your fathers made good that resolution. They succeeded; and to-day you reap the fruits of their success. The freedom gained is yours; and you, therefore, may properly celebrate this anniversary.
the repetition of "you" and "your" subtly draws a distinction between Douglass and the audience he speaks to. As a former slave, there is no sensible way he could argue that these promises were kept for him. But to his listeners, the white people of America, the "you" so to speak, that promise was kept. Douglass is showing his hand more and more as the speech draws on, before fully diving into his critiques of America.
This, for the purpose of this celebration, is the 4th of July. It is the birthday of your National Independence, and of your political freedom. This, to you, is what the Passover was to the emancipated people of God.
the key phrase "to you" brilliantly works to draw in an audience sympathetic with his arguments of emancipation without alienating the majority of his audience that would be opposed.