This study of onomancy has in many ways been an exercise in contradictions which cannot be simply resolved into a set of neat conclusions. Onomancy could be viewed as both a form of permissible natural magic and a type of illicit divination operated by demons. But whether or not onomancy was permissible could also depend on who was in possession of such a device and why it was being used. An educated physician might be absolutely free from scrutiny for practising onomancy for the most serious ends – working out if and when a sick person might die in order to make sure their mundane and spiritual needs were taken care of. However, if a physician at the royal court was suspected of predicting the death of the king or another powerful figure, and happened to have an onomantic device in his possession, onomancy most certainly would not be perceived as a permissible activity, and would likely be framed as demonic magic.

A second contradiction thrown up by this study is that onomancy was at once a serious prognostic for the prediction of life or death and potentially a fun practice tool or diversionary game for students of the quadrivium. Of course, after their undergraduate degrees these students might well go on to a higher faculty and study medicine, and so these two uses are not necessarily exclusive to particular users. A third contradiction is that onomantic devices claim to offer a definite answer – life or death, yes or no – but the corruptions contained in Latin and, later, vernacular translations meant that very often they did not. This, ironically, may have contributed to their survival, as copyists strove to find the ‘correct’ original version.

Many of the points I have made about onomancy throughout this book can, of course, also be applied to other methods of divination and prediction. But onomancy's operative elements intersected with the lively late medieval debate on universals, just at a time when the category of natural magic was postulated by philosophers and theologians in the burgeoning universities of the later Middle Ages.