Reading the website for the CASSIDY clan [http://cassidyclan.org/cassidy-history/], I discovered the CASSIDY clan were historically noted for being doctors, priests and scholars, and poets.
The earliest renowned Cassidy poet was Giolla Mochuda O Caiside. Still widely read and sung is the poetry of Tomas O Cassidy, an 18th century Augustan friar expelled from the friary as a poet and renegade priest. His most famous poem is An Caisideach Ban which is sung the length and breadth of Ireland. It is the story of Cassidy, a priest, who lusts after a fair maiden and his final wish on his death bed would be to get a kiss from her.
Sounds like a fascinating story, an expelled poet-priest roaming the countryside. I must look into it. Maybe there is a poem or novel therein.