Medieval liturgy was a complex tapestry of threads from different times and places, and, as a result, its outward forms varied across Western Europe and even within the city of Rome. By the time of Innocent II's accession to the papacy, papal liturgy had been slowly growing and changing over the course of centuries. The main forms of the liturgy were the Mass and the Divine Office. Yet the liturgy of medieval bishops had an important role in symbolically establishing their spiritual and temporal authority. An earlier study of Anton L. Mayer held that the liturgy of the twelfth century expressed the spirit of this Gothic age, exuberantly tying it to innovative trends of the time like subjectivity, individualism, and Christ-centered piety. A host of new elements had been inserted into Rome's urban liturgy in the intervening centuries. Early medieval popes had already learned that the liturgy could serve to defend their positions against internal and external enemies.