Why did Old Irish manuscripts become important to the Gaelic Revival?

Old Irish manuscripts became essential to the Gaelic Revival because they allowed scholars and writers to access and translate Ireland’s earliest literature, which had previously been inaccessible to the general public.1

The discovery by philologists of how to read Old Irish—written prior to 900 CE—enabled the translation of foundational texts and heroic tales, such as those found in the Ulster and Fenian cycles. These ancient works captured the imagination of the educated classes and provided a "Gaelic past" that served as a source of inspiration and subject matter for the rising nationalist movement.12

By incorporating the themes, imagery, and traditional metrical forms of this ancient bardic verse into their own writing, Anglo-Irish poets and authors helped stir national pride and establish the cultural groundwork for the later Irish literary renaissance.1