A theme is a dominating influence in literature whether it is in a novel or in poetry. It often conveys universal ideas which revolve around life and how it affects actions in general. It can be abstract in nature and may be implied rather than actually stated, especially in poetry. It allows the reader to follow the thread of a piece of work without becoming too involved in the subject matter itself. Poetry can be complex and there may be more than one theme. However, the main theme is revealed in the enduring lines of the poem. The subject matter of a poem is what creates the foundation from which to establish the theme. As an example, consider Edgar Allan Poe's Annabel Lee.