Adam Kirsch in Harvard Magazine:
One of the most revealing questions you can ask about any poet has to do with his sense of responsibility. To whom or what does he hold himself responsible in his writing? The poet who replies “Nothing”—who believes that the concept of responsibility is foreign to the totally free realm of art—is likely to be a bad poet. If there is nothing—no reader real or imaginary, no idea, value, or principle—with the right to hold the writer to account, then there is no way for her to know when she is writing better or worse, when she is getting closer to her ideal or straying from it.
That is why a genuine artist almost always wants to feel answerable to something. Not necessarily a person or a group, because any concrete audience is all too likely to constrict the imagination, to encourage flattery or evasion. But there is liberation in feeling responsible to an ideal reader—the best poets of the past, perhaps, or the unbiased readers of the future; or to an ethical principle—speaking truthfully, bearing witness, offering sympathy; or to an aesthetic ideal—the radiance of beauty, the genius of the language. Not until you know what a poet feels responsible toward can you know how he wants and deserves to be read.
The strength and the challenge of Seamus Heaney’s poetry lie in its willingness to admit all these kinds of responsibility at once.