Nature
Coleridge's poem imagines nature as a source of spiritual renewal and healing. The speaker focuses on the relationship between human beings and the natural world, suggesting that natural beauty can impact human psychology and relationships. He describes breathtaking natural features, such as the ash trunks "arching like a bridge," but as he continues, he emphasizes the beauty to be found even in more mundane natural settings, such as the speaker's bower. While the speaker initially dismisses the bower as a "prison," he later reassesses it, noting its "transparent foliage" and the beauty of its "richly ting'd" trees. This reassessment leads to the speaker's epiphany that nature, inherently beautiful at all times, can only be fully appreciated by people approaching it with openness and appreciation. Furthermore, by the poem's end, the speaker is able to view the natural world—both its grand and humble elements—as an emotional and physical bridge connecting him to his friends. Thus, far from representing rural life as an escape from society, the poem argues that it is fundamental in creating close-knit social groups. In contrast, the poem argues, the city is isolating and lonely. Moreover, through figurative language that makes use of religious vocabulary, Coleridge suggests that nature not only connects humans to one another, but also that it connects them to God and to the spiritual realm. This attitude towards nature is fairly typical of Romantic poetry: Coleridge's peers in the movement tended to advocate for the preservation and appreciation of the rustic and decry urbanization.
Imagination
Just as Romantic poets often described nature in worshipful tones, they also were generally advocates for the power and importance of imaginative life. The speaker of "This Lime-tree Bower My Prison" is able to escape his feelings of restriction and boredom simply by imagining what his friends are doing; what begins as an exercise in jealous resentment becomes a source of entertainment. This imaginative flight of fancy doesn't merely make the speaker feel better in the moment. It also produces a series of epiphanies and emotional maturations. Through sheer imagination, the speaker is able to better understand his friend and feel more connected to him. His imaginative journey also affects his perception, causing him to see his physical surroundings differently—the uninteresting lime-tree bower is transformed, via imagination, into a site of breathtaking beauty and liveliness. The Romantic movement is often described as a reaction against the Enlightenment, a movement stressing the importance of empirical observation and sensory perception. By arguing that imagination impacts perception, Coleridge counters this Enlightenment assumption, albeit in a complex, nuanced fashion.
