The literary landscape of the period defined in linguistic terms as Classical Old Irish (c.800–900) and Middle Irish (c.900–1200) is remarkable both for its size and for the sheer variety of its terrain. Conventionally anchored historically by means of reference to the arrival of two groups of outsiders, Vikings and Normans, marking its beginning and its end, external influences form but one of its many fertile layers. The imaginative authors who continued to embrace European intellectual activity as their predecessors had done in the pre-Viking era were firmly grounded also in an insular inheritance which they continually made new. Earlier traditions may have been revered but their value lay primarily in their continued relevance in an ever-changing environment. Thus was the heritage of which such creators were keenly aware of being a part perennially translated into a current cultural context in which it continued to serve a role, being enlivened in the process by the host of other influences to which the tradition moulders were open. Analysis of their diverse literary output, therefore, must take into account, in John Carey’s formulation, their outward, as well as their backward look.
Similarly worthy of consideration is what might be termed their inward look, manifested most clearly in the vivid allusions to other works which permeate the literature. Working within a highly developed creative tradition, each weaver had access to the same well-worn fabric of his forebears and cut his cloth with pre-existing garments in mind. The result is a patchwork of repeating patterns in new imaginative guises which can only be properly assessed in an intertextual context.