The 19th century poet, Williams Butler Yeats, wrote two works about Irish fairies
- The Celtic Twilight (1893, 1902)
- Fairy and Folk Tales of the Irish Peasantry (1888)
In Fairy and Folk Tales of the Irish Peasantry, is not only description of fairies; it is a collection of works, poems and prose, from other authors, such as T. Crofton Croker and Lady Wilde.
In this work, he divided the fairies into two broad categories:
- Trooping Fairies or Social Fairies
- Solitary Fairies
It is a good distinction to be made, though Katherine Briggs would include a third grouping, the domesticated fairies, those that include small family groups.
Social or trooping fairies are those who lived in large company, like in a clan. They were known as trooping faeries because they travelled in long processions.
These faeries are believed to be descendants of ancient, vanquished gods. They dwell in underground kingdoms or across the deepest seas.
They can range from the Heroic Faery to the dangerous and malevolent Sluagh. The chief occupations of the trooping fairies are, according to Yeats, “feasting, fighting, and making love, and playing the most beautiful music.”
Trooping fairies may range more widely in size than the solitary; some may be so tiny as to have caps the size of heather bells while others may be large enough to have intercourse with humans. Although they may have higher spirits than the solitary fairies, they still may present a threat to mortals; especially to be feared is the fearsome Scottish Gaelic sluagh, the host of unforgiving dead.
The peasantry is made up of the solitary faeries that are believed to have descended from spirits who made up all of nature. Although they had some of the same powers as their more prestigious relatives, i.e. the ability to become invisible and shape-change, they were known to be more wild and capricious. Fortunately, true encounters with mortals were relatively rare, instead their presence were most often announced by evidence of the creatures’ activity. It was believed the bending of the grass, the rustling sounds of tree branches, and the glittering patterns of frost on windows could be attributed to their nearness.
The solitary fairy usually avoid large gathering. There are many types of solitary fairy, such as banshee, leprechaun, cluricaune, brownie, pooka, etc.
Generally, they can be distinguished by the type of jackets they wore. The social fairies wore green jackets, while the solitary fairies wore red ones, but sometimes their jackets are brown or grey.
Scottish fairy folklore can also be divided in the similar fashion of solitary and social fairies.