What subjects were discussed in the scholarly writings of the filid?

The filid (singular: fili) were a professional, aristocratic class of poets in ancient Ireland who served as the primary custodians of traditional lore and learning. Their scholarly responsibilities and writings encompassed a wide range of subjects essential to the maintenance of Gaelic society:12

• History and Genealogy: They were responsible for preserving and composing works regarding the past and present glory of the ruling class, including both legendary and factual history.12
• Law: Following the 6th century, filid were tasked with instructing residents in the Brehon laws, the ancient legal system of Ireland.12
• Literature and Lore: They maintained a vast repertoire of traditional stories, including hundreds of primary and secondary tales, and were responsible for the oral transmission of native learning.12
• Poetry: Their work included official praise poetry for patrons, and by the 12th century, they also composed lyrical nature poetry and personal poems focusing on the human qualities of their patrons.1

While they initially performed priestly functions, these roles were largely abandoned following the spread of Christianity in the 5th century.12