There are many themes in T.S.. Eliot's "The Wasteland," but the primary focus of the poem is arguably the fragmented and damaged nature of the human psyche and society in the aftermath of World War I and the power of myth and the literary canon. Death and rebirth are also central ideas.
The most obvious way in which Eliot brings fragmentation into his poem is his juxtaposition of different literary texts and even languages. This reflects both the sensory overload presented by modern society as well as the breakdown of any single cohesive narrative to describe the human experience. At the same time, however, these fragments highlight the overarching history of literature and society's place within that framework.
Death and rebirth appear in many forms, including the seasons, the cycle of history, sex and love, various references to Christ and the power of water to both cleanse and baptize as well as kill all hint at a connection between creation and destruction. When combined with fragmentation, these themes hint at the possibility of renewal despite the splintered nature of the modern world.