Book review: Airmail: the Letters of Robert Bly and Tomas Tranströmer, Edited by Thomas R Smith

"It's possible that while a bird is building its nest an idea for a song it has never sung rises to its small head. So with us certain thoughts flow upward into our head only when language is being used, and used calmly." That applies particularly, continues this letter of January 1977, to those engaged on prose-poems, a miniature but intense form to which both Robert Bly and his recipient, Tomas Tranströmer, were then greatly drawn.

By this time the American and the Swedish poet have been corresponding since spring 1964. Each is regularly publishing translations of the other's poems, and seeking advice about the truest, most resonant word or phrase. Each writes of his own art, knowing that the two have in common a meditative, lyrical, metaphysical approach to both poetry and life, profoundly inspired by nature while trying to reproduce through the movement of their lines the determined workings of the psyche. Tranströmer, after all, is a professional psychologist, working in an institution for juveniles; Bly a practising Jungian whose second wife is a therapist.

Yet each writes to the other as one immersed in the concerns of his own country, and, for all his dedication to contemplative peace, morally exercised by external events. "Let's count the bodies over again": Bly encloses his famous anti-Vietnam poem in an August 1966 letter to Tranströmer.

Their exchange of letters began when Bly – himself Norwegian-American – returned from an expedition to Minneapolis to get Tranströmer's newest book and found an unanticipated letter from the author. Later they met reasonably often, staying with each other; this enables their correspondence to be warmly forthcoming about children, wives, happily accepted demands of home and work.

The book ends in 1990, year of Tranströmer's major stroke depriving him of speech, and Bly's iconic book Iron John. But their friendship continues, extended beyond themselves by this wonderful volume.