The De XII abusiuis saeculi has long been regarded as one of the three most important Irish Latin compositions of the Early Middle Ages. It stands at the apex of Hiberno-Latin learning in the seventh century, along with the De mirabilibus sacrae scripturae [DMSS] of Pseudo-Augustine (dateable to 654/655), and the anonymous Liber de ordine creaturarum—described by the great Charles W. Jones as ‘a work of magnificent conception’—which may be derivative of the De mirabilibus or may have been its source. In the ongoing (and seemingly never-ending) debate about the nature and extent of that Hiberno-Latin learning, those three texts have provided the benchmark against which the writings of later Irish authors, and of Latin writers in England and on the continent, have been measured. Of the three, the DDAS has been adjudged to have exerted the greatest influence, principally for its importance in the development of the concept of the speculum principis. Kenney remarked of it that ‘[t]he section which especially interested … continental students was that discussing the rex iniquus. And it can be said that the unknown Irish author made a real contribution to the development of European political theory’.