Answer:
In this passage from Shakespeare's play "The Tempest," Prospero is reflecting on his past and the circumstances that led him to his current situation. When Prospero says, "Me, poor man, my library / Was dukedom large enough," he means that when he had access to his books and knowledge, his library was like a kingdom to him. His books and learning were his source of power, control, and authority—comparable to ruling over a territory (dukedom). This statement reflects Prospero's intellectual and magical prowess, emphasizing how his knowledge was his primary domain and a means of exerting influence. The loss of his dukedom (his political power and status) is balanced by his newfound control through his magic and manipulation of events on the island.