"Digging" by Seamus Heaney is the Songs of Eretz Poem of the Day for May 27, 2014. A link to the poem, including an audio recording by the poet, may be found here: http://www.poetryfoundation.org/poem/177017. "Digging" first appeared in Death of a Naturalist (1966). Mr. Heaney's work has been examined multiple times in the Poetry Review, most recently on March 17, 2014 which includes a brief biography and references http://eretzsongs.blogspot.com/2014/03/poem-of-day-lovers-on-aran-by-seamus.html.
"Digging" is written from the POV of Heaney observing his father at work in the potato fields and reminiscing about his father's father at work in the peat bogs. Only the first two stanzas have a distinct rhyme scheme, as though the poet was about to compose a rhyming poem but then was distracted by the activity of his father.
The third stanza has an enigmatic, perhaps fourth dimensional, moment when the poet describes his father as coming up "twenty years away." Twenty years is about the length of a generation, so perhaps this reveals the poet's thoughts beginning to stray into the past toward the memory of his father's father. Simultaneously, the reference to twenty years may represent a clairvoyant image of his father still laboring away in the future.
The final stanza repeats the first ten words of the opening stanza in a kind of chorus and brings the poet out of his reverie. With the memory of his father's and grandfather's physical expressions of rhythm fading, the poet concludes that he will follow in his father's footsteps only indirectly by the rhythmic use of his chosen tool, the pen.