He signed his name with an X. It wasn’t just a simple letter surrounded by the indecipherable formality of an official birth certificate. No. This was a meaningful X: his mark – a letter that revealed so much about my great-grandfather to me. He was surely artistic. Confident. Proud. His X became an algebraic equation full of hidden history and unknown quantities. It was a storehouse of fact and the timeless promise of hope.

Even though he could not read or write his name, his signature X reached out to me from more than a century ago and communicated something about the history of my family. And myself. I studied his X on my grandmother’s birth certificate, where it was surrounded by church Latin and a few other clues.

Elsewhere on the document, under profession, the clerk had written “boatman.” From where I stood, I could see the Black River. Did he fish in these waters? “Boatman” had a meaning both vague and mysterious. I planned to solve this X equation by force of reason, luck and imagination. Already I could feel his life lived in this place so long ago. His X had brought me here to Ireland, the place of his birth.

Meg and I arrived in Dungarvan, County Waterford, after traveling in circles through the towns and villages of the Emerald Isle. We both felt strangely at home here, where cars crawled along on the left side of the road and where the best way to travel is by bicycle or by foot.

It is a great joy to walk through the villages of your ancestors. And walk we did. Along the beach at Glencolumbkille, where fishermen still ply the North Atlantic in currachs that bob between the tidal waves. In Sligo we sipped ale with the locals at Ellen’s pub and learned that everything William Butler Yeats wrote about was true. Here Queen Maeve and her mystical cohort appeared with regularity. There in the shadows cast by the glowing turf fire, I had no doubts. The next morning we walked to the peak of Knocknarea to overlook the emerald quilt of three counties spread before our tired feet. We felt like gods enchanted by the cool Atlantic mist.

Later, we spoke of poetry in the town pub, where the locals could recite the Yeats canon by heart. It was there I abandoned the safety of American logic for the twisted gyres of the Celtic imagination, and I haven’t traveled in a straight line since.

On we passed through Galway and turned east. So many castles and manor houses were collapsing in ruin, but never torn down. They were eternal reminders of history and the troubles that others call war.

Finally we arrived in Dromore near the birthplace of my grandmother Mary Osborne. It was a village so small we could only find it by rumor and luck. We climbed the unmarked hill to stand in the crumbling cottage where she was born. All around us the local sheep grazed as they had a century ago. Later we visited the simple church in Aglish where she was baptized. Still later I held the register where her name was written alongside her father John.

At the onset, I thought I had traveled here to discover my heritage. Now I felt the river in my veins and spoke the poetry in my heart. My great-grandfather had surely reached out to bring me here by giving me a grand equation to solve. His X equalled an eloquent gesture made so long ago. A man’s life reduced to a single letter that now enriched mine tenfold.