Principia is a mandatory exercise in the medieval universities that requires that at the beginning of each academic year, the bachelors enrolled to obtain the title of doctor in theology had to engage in a public debate with their colleagues. The main aim of the proposal was to understand how and why this new academic practice featuring the direct interaction between bachelors of theology at Paris became in the course of the fourteenth century one of the most important events in the academic calendar of universities all across Europe. Now, after five years of intense research, we have come to the conclusion that the success of this exercise resulted from the freedom to choose the topics of debate, the requirement to confront publicly the theses of the other speakers, the opportunity to earn a reputation before a wide audience, and the entertainment value of the event as a way of opening the academic year in an exciting way. We have now demonstrated that by the second half of the fourteenth century, when many new universities were founded, Principia had become a fixed feature of the curriculum not only in Paris, but also in Oxford, and its adoption elsewhere is understandable. Nevertheless, the enthusiasm with which the genre was perpetuated in Prague, Vienna, Krakow, and elsewhere is also due to the fact that an oral competition lasting several days before a crowd of students and professors, allies and opponents, in which false courtesy, sarcasm, and irony joined argument and auctority to create an intellectual tournament, a joust with ideas instead of lances.
Principial reports are therefore like Russian-dolls texts, encompasing within them ideas and even words from the other participants in the debate. Among the general findings, two can be named here: the protestatio and the gratiarum actio. The protestatio is an oath that bachelors took near the start of the debate, wherein they publicly proclaimed, in front of the audience, that they would respect the institutions (university, Church, royal court, etc.), they would exercise self-control in avoiding known errors or any heresy, and that they would show courtesy toward their fellow combatants. At the end of the debate, the gratiarum actio is the instant when each protagonist of an academic act thanked his public for attending and sometimes for supporting his performance. In this he could display his gratitude to the Church and its saints, the university and its doctors, his mentor, his colleagues, and even his family for accompanying him while he carried out his official acts. We find in this custom the roots of our modern acknowledgements that open PhD theses and books. Incidentally, it was surprising to identify how many actions in our present academic are linked in some way to these medieval Principia: evaluation by peer reviewers, the pleasure and emotion of public performance in presenting research results, academic jealousy, persistence and sometimes obstinance in defending ideas, and the joy of thanking the people and institutions whose support led to success.