Final answer:
Frederick Douglass supports his assertion about the awakening to freedom by focusing on the profound impact of his personal contemplations on his situation.
Step-by-step explanation:
The author Frederick Douglass supports his claim that the "silver trump of freedom had roused [his] soul to eternal wakefulness" primarily by describing the effects of thinking about his situation. This can be seen in passages where he shares his inner reflections on freedom, the realization of his rights, and the deep longing for liberty.
These reflections embolden him and crystalize his resolve to not just be free in thought but in reality as well. His descriptions of how the very thought of freedom made everything else bear witness to his wretched condition show how his consciousness has been awakened to the injustice of his enslavement and the relentless pursuit of freedom.