The change from past to present tense in the final couplet signifies an inevitability to the foe’s death. It is as if the speaker is an impartial witness, viewing the scene in the morning “light” of pure reason. In the final stanza, Blake uses night and day as representative of the contrasting states of the foe and the speaker, respectively. Again, a mention of Blake’s Urizen, the god of reason, is apt here. Though Urizen baits the foe with his own feelings of contempt, the god ultimately holds the human accountable.

The “pole” could refer to the Northern pole or the Northern star, also known as the “pole star.” This line draws on the classic metaphorical duality of light as reason and darkness as lack of reason. The concealment of a “true North” by which to navigate signals the foe’s lack of clarity and reason in deciding to eat the apple.

The setting of the garden alludes to the Garden of Eden, further emphasizing the parallel between the story of the poem and the episode of original sin in the book of Genesis. The word “stole” has two registers. Literally, the foe sneaks into the garden while “stole” also connotes an act of theft, which evokes Eve’s theft of the fruit of knowledge. Once again, all responsibility is placed on the foe, even though it is the foe who ultimately dies from the speaker’s wrath.

Blake’s use of the verb “knew” is key. The foe understands the nature of the apple, placing all subsequent responsibility on the foe, rather than the speaker. The foe’s knowledge parallels that of Adam and Eve, who understand their sin before eating the apple in Eden.

The apple serves two primarily symbolic functions. The apple is the result of the speaker’s long-harbored, unexpressed wrath. The image offers an appropriate touch of redness, underscoring the tone of rage. The apple also serves as an allusion to the fruit of the knowledge of good and evil in the book of Genesis. Satan offers Adam and Eve the fruit; their to decision to eat it marks the “original sin.” Thus the apple is the hinge between innocence and experience, to use Blake’s terminology.

The speaker’s decision to cultivate the tree of wrath with water and sun represents a sort of passive aggression. The speaker’s feelings of wrath are an internal state which, left unaddressed and unchecked, become external. It is the wrath’s external form, the tree with its poisonous fruit, that becomes a danger to others, in this case the human “foe.” On one level, the tree of externalized wrath reveals the particular character of the speaker, a Satan-like figure who deceives humanity. On another level, all humans can be guilty of handling their inner emotions in a way that becomes poisonous to the outside world. The character of Satan serves to illustrate this broader theme.

Through his art and poetry, William Blake constructed his own mythological system, drawing on Christian, Greek, and Norse traditions. One of Blake’s central gods is “Urizen,” a character who mirrors the biblical Lucifer, or Satan. Like Lucifer, Urizen is a fallen god who displays a contempt for humanity and a dedication to pure reason (“Urizen” is a verbal play on “Your Reason”). One of the poem’s themes is the separation between the speaker and “my wrath,” a chasm which hints of Urizen’s separation from the realm of emotion.

According to Christian cosmology, the angel Lucifer rebelled against God and was cast down from heaven. Lucifer thus became Satan, the deceiver of humans. In Blake’s poem, the speaker’s initial wrath towards “my friend” alludes to Lucifer’s rebellion against God. The next object of wrath, “my foe,” is Satan’s eternal prey, humanity itself. The words “friend” and “foe” establish a hierarchy. Satan is subservient to God—a “friend”—but has power over humanity—his “foe.”

With repeated uses of “I,” Blake places the speaker at the poem’s center. Scholars have identified the speaker as a representation of Satan. Indeed, the central theme of “Songs of Innocence and of Experience” is humanity’s fall from grace to sin in the Garden of Eden, as told in the biblical book of Genesis. The poem’s story depicts this very fall, telling it from the perspective of Satan, a fallen figure in his own right.

As with much of his verse, Blake chose to set “A Poison Tree” in tetrameter, a four-beat meter with a song-like rhythm. So musical are Blake’s poems that many of his works—“A Poison Tree” included—have been set to orchestration by composers such as Ralph Vaughan Williams. Also typical of Blake is the use of the AABB rhyme scheme. These rhyming couplets lend the poem a tone of simplicity, akin to that of a nursery rhyme. The innocent tone contrasts sharply with the malicious actions of the speaker.