A few years ago Diarmuid Breathnach called in on me in Connemara, looking for information on a Donal O Fotharta, who had published a little book of folk tales and songs from the Ballyconneely area in 1892, when Irish was still spoken there. All I had to offer was the whereabouts of the former National School, now a holiday home, in Calla near Bally conneely, where he had taught.

So we drove to Calla, searched an overgrown cemetery for O Fotharta's grave, without success, talked to the owner of the old schoolhouse, who referred us to the parish priest, who passed us on to the oldest resident, who could remember only that all O Fotharta's former pupils "had great Irish". An enjoyable day up and down the boreens, but not rich in clues to O Fotharta's life story.

However, a year later appeared the fourth volume of Beathaisneis (biographies), including a crisply formulated account of the old teacher, evidently the fruit of many such diligent days as the one I had witnessed. Now the fifth volume is to hand, in the same staid and sturdy format as its predecessors (300 pages or so of two columns of small but clear print), completing an irreplaceable contribution to that imagined work of national biography Breathnach and Ni Mhurchu referred to in the introduction to their first volume as "easpa laethuil", a daily lack.

The five volumes comprise seven hundred biographical essays on people active in the Irish-language movement whose deaths fell in the period 1882-1982, with an appendix bringing the roll call up to 1996, of whom perhaps 60 are fairly familiar names and many of the rest virtually unhonoured, until now, in the collective memory.

Does O Fotharta matter? His antiquated little collection of tales, songs and riddles, Siamsa an Gheimhridh (Winter Entertainment), had solved a few puzzles for me in my work on local place names, ministering to my pedant's glee in eliciting obscure facts from even obscurer sources. I first came across him as a correspondent of the Aran Islands schoolmaster David O'Callaghan, who taught Liam O'Flaherty that there was such a thing as written Irish.

So there is a tenuous connection between O Fotharta and Duil, the short-story collection through which generation after generation of schoolchildren enter into Irish-language literature. Without those hundreds of modest, laborious enthusiasts we would not now have access to what O Fotharta called "an teanga bhinn bhriomhar, an teanga treun tuilteach, an teanga uasal ard arsa ar sinnsear fein" ("the sweet lively tongue, the strong overflowing tongue, the noble high ancient tongue of our ancestors themselves"). This is the rhetoric of his passionate and idealistic age - but there isn't a word of it I could quarrel with as a description of Irish; I don't feel excluded by those "ancestors" even, for to me ancestors are the former inhabitants of whatever ground I find myself inhabiting, and learning something of their language is part of my investment in that ground.

It is reassuring that completion of Beathaisneis has been marked by the award of Gradam Bhord na Gaeilge, for previous volumes of this important work attracted little notice, and no publisher has as yet proposed an English-language selection. The elements of anti-modern reaction and nationalistic introversion in the mind-mix of the past generations of Gaeilgeoiri still inhibit recognition of what was generous and creative in them. But Irish, long constricted in polemical narrows, is again a sweet, strong and overflowing tongue, and we should be able to welcome it, like any other language, as a unique occasion of joy. The anxious ideologies attending its present life-or-death situation arise inescapably, but only after and because of that possibility of joy.

Tim Robinson is the author of Stones of Aran