THE JOYOUSLY engrossing volume of The Letters of Seamus Heaney, published last year, includes the poet’s side of 23 exchanges with another great Irish writer, the playwright Brian Friel. The two shared drafts of new work: and, as the book details, on 24 November 1975, Heaney wrote from his then home – Glanmore Cottage, Ashford, Co. Wicklow – after receiving a copy of Friel’s play in progress.