 Besides this more technical layer, medieval authors also discussed extensively the very nature of the notion of consequence: what counts as appropriate grounds for a valid consequence, adequate definitions, subdivisions of kinds of consequence etc. In what follows, the predominant focus will be on the ‘philosophy of logic’ side of medieval theories of consequence, i.e. how they articulated this very notion, rather than on spelling out the exact inferential rules endorsed by the different authors. But some medieval treatises on consequence also contain a high level of technical sophistication, even though the language used is the regimented academic Latin of the time – the only symbolic device present is the use of schematic letters, which in fact dates back to Aristotle.