Centuries of Roman jurisprudence were assembled in the great Byzantine collection, the Digest, by Tribonian and the other editors. Roman law became more formal when during the Renaissance of the twelfth century it came to be taught in the first universities, starting with Bologna and the teaching of Irnerius. The main channels of expansion were through the Glossators and post-Glossators, who commented on the main texts and on later legislation by the Holy Roman Emperors, which included “feudal law,” but also by notaries and other proto-lawyers. Christian doctrine also became part of the “Roman” tradition, and canon and civil law were taught together in the universities as “civil science.” According to the ancient Roman jurist Gaius, “all the law which we use pertains either to persons or to things or to actions,” three categories that exhaust the external human condition—personality, reality, and action. In the nineteenth century, the study of Roman law lost its ideological power and became part of philology and history, at least so concludes James Whitman.