The reader must search for the theme of the poem, and only from learning about Plath's own life can ascertain that the subject. Plath's esoteric references are less accessible than Lincoln's musings about suicide, death, and hell. However, both Plath and Lincoln do directly mention death in their poems. Lincoln's narrator mentions in line two of "Suicide's Soliloquy" his "carcass" and then in line three, the "buzzards" that "pick my bones." Likewise, in the second and third lines of "Edge," Plath describes "Her dead / Body." Both poets focus on physical mortality with graphic descriptions of darkness and despair. Both also weave imagery of life and death to create complexity and lure the reader. Plath's subject matter is a dead woman who "wears the smile of accomplishment" after her death (line 3). Yet her life is "over" and references to blood and bones provide morbid motifs. Lincoln's first-person narrator is ruminating over his possibly spending eternity in hell. The narrator of "Suicide's Soliloquy" does not embrace death as readily as the woman in "Edge" but nevertheless does mention the relief from pain that death provides. For example, the narrator speaks about that which will "ease me of this power to think," and also refers to being "driven...to this end." Plath's narrator claims that the dead woman was "used to this sort of thing."

The morbid subject matter...

That the two poets wrote a century apart has little bearing on the content of their work. Also, their time period does not necessarily determine how accessible their work is. Lincoln's poem uses some out of date diction and a formal poetic structure including an ABAB rhyme scheme. However, Lincoln's subject matter is immediately apparent. The reader knows "Suicide Soliloquy" is about suicide not just because suicide is embedded in the title then because of the frank first-person references to morbidity and mortality throughout the poem. Plath's "Edge" is less overtly about suicide than it is about death. The narrator describes a dead woman but not necessarily one that took her own life.
Plath's poem is difficult because of its free-form style and cryptic symbolism. She uses a metaphor for a dead child that is "coiled, a white serpent." The "pitcher of milk" mirrors the "white" color of the dead child and of the moon. Plath's poem is powerful and rich with symbolism. Lincoln's poem is difficult more because of diction and style. The lofty language and elaborate references to hell are anachronistic in the 21st century, whereas Plath's juxtaposition of life and death seems more modern. Both poems offer challenging and deeply personal insights into tricky topics like death, psychological suffering, and suicide.