In modern times the topic of medieval heresy has always aroused special interest among scholars and to some degree the general public. One reason may be that heretics were a minority and they were persecuted. The other reason is probably that the phenomenon of heresy still remains mysterious to us. Although we know more and more about heretics, many aspects of their life remain unclear. This is caused by the character of the sources that have come down to us. Heretics had to live in hiding, and they had to protect their own texts. On the other hand, the Catholic Church had its own purposes and was not particularly concerned with portraying its enemies in an unbiased way. Like it or not, we have to rely mostly on the sources written by Catholic priests to refute heterodox teachings.

The reading of anti-heretical treatises plays therefore a crucial role in apprehending heresy. Usually our approach is based on historical methods – in the texts we search for all the facts about the doctrine in question and historical events related to the particular religious movement. However, in my opinion, we should focus not only on the contents, but also on the medium that was used to convey them – the language. I think that the language of such literature reveals the attitude to the topic, although not always explicitly. And not only is that the attitude of an author, but also, to some extent, the attitude of a society. In the context of anti-heretical discourse it has a special meaning, because all the authors belonged to one institution, the Catholic Church, and represented its interests. What is more, that group had considerable control over that society, and since the Church was operating across Europe with a highly organised administration, its texts could spread widely and easily. Hence all the ideas or approaches supported by the Church could reach and influence wide masses of the faithful in a relatively short time. And the main language of the Church, Latin, was the one universal language in Europe at the time.

Latin in the middle ages had some special features. It was the second language for all its users. Moreover, it was closely related to the scholastic way of teaching based on lectio and disputatio.