Final answer:
Frederick Douglass utilizes the excerpt to illustrate the stark contrast between the nation's joyous celebrations of freedom and the grim reality of enslaved individuals, with the aim of inspiring anti-slavery sentiment.
Step-by-step explanation:
In the excerpt from Frederick Douglass's speech, he uses vivid language to underscore the painful contradiction between the celebration of national freedom and the continued enslavement of millions. Douglass elucidates the agony of enslaved people hearing the 'jubilee shouts' of freedom that they cannot partake in, thereby highlighting the hypocrisy and cruelty of celebrating liberty while condoning slavery.
By doing so, Douglass employs this excerpt to appeal to the conscience of his audience, provoke deep reflection, and - ultimately - galvanize them towards anti-slavery action. The poignant image of the 'mournful wail of millions' serves as a powerful backdrop to the apparent national joy and is intended to evoke empathy, stir emotions, and spur change among his listeners.