"Deep in Earth" is a couplet, presumably part of an unfinished poem Poe was writing in 1847. In January of that year, Poe's wife Virginia had died in New York of tuberculosis. It is assumed that the poem was inspired by her death. It is difficult to discern, however, if Poe had intended the completed poem to be published or if it was personal.
Poe scribbled the couplet onto a manuscript copy of his poem "Eulalie." That poem seems autobiographical, referring to his joy upon marriage. The significance of the couplet implies that he has gone back into a state of loneliness similar to before his marriage.