The eleventh century can be seen as a time of rupture and crisis in European history. Although law before the eleventh century consisted mainly of oral tradition, written law also carried some weight, especially church (canon) law. The eleventh century saw the beginnings of an economic transformation in Europe which recent researchers have dubbed the commercial revolution of the middle ages. The commercial revolution inevitably created a demand for a rational law of contract and a reliable credit system; and this could only happen on the basis of secure and generally accepted legal texts. The transformation and new development of law was impelled not only by economic, but also by religious factors. The end of the eleventh century, the time of the Gregorian reform, saw the rediscovery of the Digest and the first attempts to teach Roman law. During the Gregorian reform, the Pseudo-Isidorian Decretals were much consulted, and this aroused interest in the procedural rules for ecclesiastical courts.