The De XII abusiuis saeculi, or On the Twelve Abuses of the Age, is a treatise from seventh-century Ireland predominately concerned with the orders of society and the proper roles of those orders within society. Its author formulates twelve abusive expressions or abusiua to identify behaviour that undermines the Christian message. In doing so, the treatise connects abusiua to abuses of God's Law and of the divine calling of different groups within society. Failure to avoid these abuses will result in the suffocation of justice and the damnation of an entire Christian society, without recourse to a defence before the divine judge.

The treatise outlines the orders in twelve distinct categories, appearing to move from six categories of the individual—the scholar, the old, the young, the wealthy, the female, and the aristocrat—to six more ‘public’ categories—the Christian, the poor, the king, the bishop, the common folk, and the people as a whole. The rhetoric is powerfully shaped by appreciation for antithesis, pairing a positive role with the lack of a required virtue or the presence of a destructive vice. The treatise subsequently unpacks the adverse impacts of the select examples, followed by the benefits to society if virtuous behaviour is embraced and wrong behaviour is rejected. This style—whereby antithesis introduces negative criticism followed by positive example—is much favoured in an insular context. Indeed, one of the earliest surviving medieval ‘mirror for princes’, that of Gildas's De excidio Britanniae (dated variously 479–550) and critical of the behaviour of kings and clerics, adopts similarly antithetical criticism followed by positive example. It may well be useful to regard DDAS as a broader ‘mirror for society’, although structured in a more systematic fashion.