This project aims to research the 'regulae juris' developed by the medieval learned jurists The 'regulae', short and memorable Latin "maxims", were precursors of our general principles of law As such they have had an enormous and lasting importance in the Western legal tradition Modern legal theorists and even judges and attorneys continue referring to them up to this day The objective will be to establish the origin, evolution and system of the 'regulae', taken holistically The project is innovative in that it will employ the same method as the medieval jurists themselves were using - the dialectical method of analysis and synthesis Not only the project results will be published, but also preparatory materials will be published online The project will provide a historical context for the 'regulae' and reveal their true meaning in the legal system In this way, it will achieve a major scientific breakthrough, uncovering the foundations of all the modern Western legal systems and, potentially, starting a whole new series of research projects in the history of European law and in jurisprudence