What was the most important university subject in the middle ages?

By "Arts" the degree was referring to the seven liberal arts - arithmetic, geometry, astronomy, music theory, grammar, logic, and rhetoric. These were all taught in Latin, both speech and text, and students were expected to be fluent and able to converse and debate intelligently in the language. The trivium comprised the three subjects which were taught first - grammar, logic, and rhetoric. These three subjects were the most important of the seven liberal arts for medieval students