Seamus Heaney … has learned his trade so well that it is now a second nature wonderfully responsive to his first. And the proof is in "Field Work," a superb book, the most eloquent and far-reaching book he has written, a perennial poetry offered at a time when many of us have despaired of seeing such a thing.

Heaney published his first book of poems, "Death of a Naturalist," in 1966. It was a book of promise, and of promises made mostly to his father, family, race and country. A local book, in the sense that our household gods are local…. In his second book, "Door Into the Dark" (1969), the dark is a blacksmith's forge, to begin with, and then the other forms of darkness that shadow the security of earth, time and the seasons. One poem speaks of "the smells of ordinariness." The art of poetry is likened to...