Picture the poet sitting at his writing desk looking out on his father digging the flower bed. All that separates them is a single pane of glass. Whilst seemingly insubstantial, this barrier between father and son is at the very heart of Digging and leads to the metaphor "snug as a gun". Heaney likens his pen to a weapon with which to protect himself from criticisms about his choice of career.
A large section of Heaney's body of work deals with separation and isolation. His isolation from family is clear on his return from school for his brother's funeral in "Mid-Term Break"; his fears about farming are explored in "The Barn" and "Early Purges"; his admiration for his father and frustration at his own lack of skill are presented in "Follower" whilst his lack of understanding of nature is expressed ironically in "Death of a Naturalist". Digging is a coming to terms with all these issues. Essentially circular in structure, the changes made between the first lines and the closing lines reveal that Heaney has found an answer. He may never be as skilled as his forebears in working the land but his skill with a pen can recreate that lifestyle, keep it fresh and ever-present in the minds of his readers.
The poem begins in the present. Heaney is writing; his father is digging. This is as it always is. It is important to note that Heaney "looks down" at his father's "straining rump". Literally his position at the window is elevated but we also get the sense that Heaney somehow feels superior to manual work and that he is not comfortable with this feeling. The description of his father's backside as a "rump" aligns him with the natural world.
The next stanza presents us with a flashback to previous years before his father's retirement from farming: "Bends low, comes up twenty years away". We move effortlessly from flowerbed to potato drills allowing Heaney to describe his father's skills. The paradoxical "coarse boot nestled" shows the physicality of digging alongside the love for it.
Heaney uses a two line stanza beginning with the exclamatory "By God" to take us further back to his grandfather's digging skills. The exclamation and the conversational tone add a feeling of being with Heaney as he reminisces. Neatly Heaney has taken us back to his forefathers to show that working with the land has always been a tradition in the family. He has broken this chain by choosing to become a writer.
The next stanza is a memory of visiting his grandfather as he cuts peat from the bog. The "bottle corked sloppily with paper" reflects Heaney's clumsiness in practical matters but also a different use of paper to the one he is really skilled at. This is a family proud of their achievements which are measured by a spade and the ability to handle one: "My grandfather could cut more turf in a day than any other man on Toner's bog".
The penultimate stanza reveals the difficulties created by Heaney's wish to write. The "curt cuts through living roots" are not only the sharp edge of the spade cutting through living turf. They are the sharp words spoken as Heaney cuts his ties with his family's traditional means of earning a living.
And so we return to the beginning lines of the poem with the significant change from "as snug as a gun" to "I'll dig with it". Heaney recognizes that his skill with a pen is comparable to that of his forefathers with a spade. He also realizes that he can continue the love for skilled work with the land through his writing.
Just as his grandfather was "digging down and down for the good turf" so will Heaney dig down and down for the good stuff that makes his poetry so exquisite.