The apple serves as the physical manifestation of the speaker’s “wrath” (Lines 2 & 4). It is, in effect, the “fruit” of all of the effort the speaker has put into feeding and growing his festering hatred. The apple serves as a direct allusion to the story of Adam and Eve in the Garden of Eden. In this biblical tale, God creates Adam and Eve to live together in Paradise and to serve as stewards over all creation. The only rule Adam and Eve are given is to avoid eating the fruit of the Tree of Knowledge of Good and Evil in the center of the garden. Satan uses this fruit to tempt Eve into taking a bite, and Eve subsequently passes the apple to Adam for him to taste, as well. It is this transgression which, in the traditional Christian tradition, marks the beginning of original sin and is the reason Adam and Eve are cast from the Garden by God. This occurrence in the Book of Genesis symbolizes the loss of human innocence.

Just as the apple serves as the means of destruction and deception in the Book of Genesis, so it does in Blake’s poem.