"she balances the book on her lap and begins to read."

The poem that Lexie is reading in the garden is by John Donne, titled Death Be Not Proud.

John Donne would be on any under-graduate literature course, which may explain why Lexie has the book. The theme of the poem is the everlasting life of the human soul, which as you will see as you read on, has a relevance to this novel, and especially to Ted.