From O'Sullivan's notes to the song.

In this song we have the unusual and attractive concept of the Spirit of Drink as a Dark Slender Boy who accompanies his protégé everywhere. The author of the conceit was a Munster poet of the mid-eighteenth century named Seán Ó Seanacháin (John Shanahan), whose eccentric character and general irresponsibility earned for him the sobriquet of "Seán Aerach" or "Flighty Jack". According to the account given by O'Curry to Petrie, he was a native of Tulla, County Clare, who settled down in the neighbourhood of Glin, on the estuary of the Shannon in County Limerick.

Aoibhill, mentioned in the third verse, was the Fairy Queen of Thomond in Irish mythology; and her palace, Carraig Liath or The Grey Rock, is a hill overhanging the Shannon about a mile and a half above Killaloe, on the Clare side of the river. She appeared to Brian Boru on the battlefield of Clontarf (1014), predicted the outcome of the battle and informed the king of his impending death.

*Pronounced Eevil.