The poem opens with the statement, "I will arise and go," which is an allusion to the Bible. This phrase appears word-for-word twice in the King James Bible, which Yeats likely used for worship, as he was a Protestant. It also crops up in several places in slightly modified forms—for instance, "let us arise and go," and later, "we will arise and go," both in Genesis, the first book of the Old Testament. As a result, it is unclear if the speaker is invoking a particular story or biblical language more broadly. Regardless, the allusion signals that the speaker is embarking on a spiritual journey
The famous Parable of the Prodigal Son contains the exact phrase in question. Because it is the most familiar biblical story that does so, the following discussion will serve as an example of the meaning that the allusion might bring to certain readings. Jesus shares the parable with his disciples in Chapter 15 of the Book of Luke. As the story goes, there is a man with two sons, the younger of whom has traveled far from home and squandered his inheritance by living an extravagant lifestyle. Eventually, this son runs out of money, at which time a severe famine sweeps the land, leaving him destitute.
After failing to make a living as a lowly swineherd, he vows to return home:
I will arise and go to my father, and will say unto him, Father, I have sinned against heaven, and before thee,
And am no more worthy to be called thy son: make me as one of thy hired servants.
His father meets him with forgiveness and generosity, celebrating his return. When the older son protests, his father explains, "It was meet that we should make merry, and be glad: for this thy brother was dead, and is alive again; and was lost, and is found."
By recalling this story, the allusion indicates that disavowing one’s worldly possessions and returning to nature is analogous to the prodigal son renewing his devotion to God and returning home. The direct replacement of “father” with “Innisfree” lifts nature up as a godly, healing, and forgiving force.
The allusion reappears at the poem's conclusion, displaying the speaker's determination to find spiritual fulfillment through living a modest life on Innisfree.