1. Faith and Doubt: Arnold explores the conflict between religious faith and the increasing skepticism and doubt that were prevalent in the Victorian era. The poem reflects the speaker's uncertainty about traditional religious beliefs and the loss of faith in a world shaped by scientific advancements.
2. Isolation and Loneliness: Arnold conveys a sense of isolation and loneliness experienced by the speaker and humanity as a whole. The references to the sea as "the unplumb'd, salt, estranging sea" and the "ignorant armies" suggest the vastness of the universe and the insignificance of human existence.
3. Change and Transience: The poem acknowledges the constant change and transience of human life and civilization. Arnold draws parallels between the ebbing tide and the passing of time, highlighting the impermanence of human endeavors and the inevitable decline of societies.
4. Love and Human Connection: Despite the pessimism and doubt expressed throughout the poem, Arnold offers love as a source of comfort and connection in an uncertain world. The speaker finds solace in the presence of his loved one, emphasizing the importance of human companionship and emotional support in the face of existential challenges.
5. Nature and Beauty: Arnold also engages with the theme of nature and its significance in human experience. The poem's setting by the sea and the vivid imagery of the natural world provide a backdrop for the speaker's reflections on faith, doubt, and the human condition.
Overall, "Dover Beach" explores the complexities of human existence, grappling with issues of faith, doubt, isolation, and the search for meaning in a changing and uncertain world.