In Seamus Heaney's poem "Digging," the speaker describes his ancestors' digging using imagery and considers his own writing as his form of "digging."
The speaker begins by referencing a more figurative form of digging, as his "squat pen rests" between his fingers, "snug as a gun." This short stanza includes some imagery, as we can picture the speaker holding his pen. The simile "snug as a gun" also conveys how tightly he is holding the pen and how it seems to fit there.
Most of the imagery, however, is in the stanzas of the poem where the speaker describes his father and grandfather literally digging. Stanzas three and four are heavy on imagery:
Till his straining rump among the flowerbeds
Bends low, comes up twenty years away
Stooping in rhythm through potato drills
Where he was digging.
The coarse boot nestled on the lug, the shaft
Against the inside knee was levered firmly.
He rooted out tall tops, buried the bright edge deep
To scatter new potatoes that we picked,
Loving their cool hardness in our hands.
Because of the details the speaker describes, the reader can imagine the speaker's father squatting (a nice reference to "squat pen" in the first stanza) and "rhythm[ically]" shoveling in gardens and crops. The father's "coarse boot" and its placement on the soil is described using imagery, as well. The speaker even conveys how it felt to hold potatoes, "their cold hardness in our hands."
The speaker next says that his father was very good with a spade, as was his father before him. This marks a transition to the speaker's description of his grandfather's digging. The speaker explains,
My grandfather cut more turf in a day
Than any other man on Toner’s bog.
Once I carried him milk in a bottle
Corked sloppily with paper. He straightened up
To drink it, then fell to right away
Nicking and slicing neatly, heaving sods
Over his shoulder, going down and down
For the good turf. Digging.
The description of the speaker bringing his grandfather a gottle of milk, his drinking the milk, and his continuing to "Nicking and slicing neatly" paints a vivid scene in the reader's mind. The rhythm of the spade is captured well in the last few lines of the stanza as the speaker portrays his grandfather's digging.
Next, the speaker uses imagery to recall his memories associated with his father's and grandfather's actions. He writes,
The cold smell of potato mould, the squelch and slap
Of soggy peat, the curt cuts of an edge
Through living roots awaken in my head.
But I’ve no spade to follow men like them.
The imagery and alliteration
in this stanza work together to convey the vivid memories the speaker associates with his ancestors. He recognizes, though, that he is not talented in that kind of work. The poem becomes more figurative once again as it concludes. The speaker has "living roots" in his mind that inspire his poetry, but he cannot literally dig the way his father and grandfather did. Instead, he digs into his memories to create poetry. So, the speaker ends the poem by going back to the original image of him holding a pen and makes the comparison more direct by saying, "I'll dig with it."