Modernism and post-modernism are two aspects of aesthetic modernity reflectingsome of the spiritual crises of the western civilization as resistance against thescientific modernity. These two are similar or the same to each other in seeing themodern world as fragments and discontinuities with pessimistic tone, the reality asrelativity, and the language as lack.
By contrast, many differences between the two can be seen as well. Forexample, modernism reflects Elite's taste of high culture while postmodernism isimpatient with Elite's taste of ideas. And also, modernism hands down humanismand enlightenment while postmodernism rejects the so-called humanism andenlightenment. More likely than not, however, the foremost difference will be thatmodernism has the spirit of betterment by a kind of stoic attitude throughself-criticism hoping for the birth of the hero who searches for the spiritual father,while postmodernism reflects a kind of Epicurism emphasizing 'seize the day' byaccepting the commercial, technological and scientific values.
It follows that modernism tries to expand freedom of more people throughdigging inner reality while postmodernism tries to expand equality of more peoplethrough de-constructing the concept of hierarchy of the western civilization.
I think that Seamus Heaney's Seeing Things is characterized by the combinationof modernism and post-modernism: his poetry contains the characteristics ofmodernism in respect that it continuously reflects the pursuit of tradition. At thesame time, it includes post-modern aesthetics in respect that Squarings of SeeingThings transforms the concrete into the abstract by de-constructing some of the fixedmeanings, from which readers can enjoy the entire freedom.
My last conclusion is that Seamus Heaney's Seeing Things reflects not only hispursuit for the past tradition but also his desire to de-construct it. In brief, hispoetry reflects some ambivalence: the search for the father and killing him, waitingfor Godot and searching for light, freedom, equality and song.