The poem begins in the present tense as Heaney describes seeing his elderly father straining among the flowerbeds, then goes into the past tense when he remembers his father and grandfather at work. The last two stanzas return to the present, when Heaney realises that his work is to write. The final line, however, is in the future tense, to emphasise Heaney's determination 'I'll dig'.
He then describes his father and his grandfather as they work, he describes to us their movements and actions and they dug, 'Stooping in rhythm through potato drills' this shows he was extremely skilled working as efficiently as possible.
He was also proud of his grandfather, who was so keen to work that he hardly stopped when Heaney brought him some milk. 'To drink it, and then fell to right away' this show how hard he worked. His work was precise - 'nicking and slicing neatly' and he was strong 'heaving sods over his shoulder.
Heaney does not explain exactly why he has 'no spade to follow men like them'. Does he think he is not physically strong enough for the work? Or does he think his father and grandfather may not approve of him cultivating the land.
There is quite a lot of alliteration in digging e.g. 'curd cuts' digging down and down' and 'the squelch and slap of soggy peat' this gives the poem life it makes it more interesting to read. The opening simile is striking - Heaney's pen is 'snug as a gun'. It shows how perfectly the pen fits his hand, this shows how well suited Heaney is to write. (In the fourth stanza, Heaney describes how perfectly his father's body is in tune with the spade, showing how well suited he is to dig.) The gun image also suggests the strength of the pen, it is a weapon for writing.
There is a writing technique called enjambment which means lines in a poem that run on from on to another without a punctuation or pause. There is an example of this between the second and third stanza. 'My father, digging.'
'I look down Till his straining rump among the flowerbeds Bends low, comes up twenty years away, Stooping in rhythm' Heaney looks down from his window to see his father digging - and then we find he is looking back twenty years. The pause between the stanzas indicates the gap in time.
The penultimate stanza appeals to our senses. Heaney gives us the cold smell of 'potato mould', the sound of 'squelch and slap Of soggy peat', the sight of the 'curt cuts'. This helps to make what he describes more vivid, this gives very good imagery.
The final stanza almost brings the poem round full circle. It repeats the opening lines: 'Between my finger and my thumb The squat pen rests.' Yet the gun image is replaced by 'I'll dig with it.' His pen becomes a metaphorical spade. This suggests that his pen is his tool, just as the spades were tools for his father and grandfather. It also suggests that Heaney wants to 'go back to his roots' to dig into his past through his writing.
There is a lot of repetition in the poem, the words "dig' and "digging" are used. This shows the importance of digging, for peat and potatoes, it also show how it is part of his families heritage and has been going or generations.
A few lines near the beginning of the poem have fairly conventional rhymes: thumb/gun, sound/ground/down; thereafter the poem is unrhymed, though there are repeated sounds such as the echoing ing sounds in 'nicking and slicing neatly, heaving sods'