
Biography
Next to nothing is known about the life of Marsilius of Padua, or Marsilio dei Mainardini. While still a young student he was torn between the pursuit of legal studies and medicine. Eventually he would become a medical doctor and the rector of the University of Paris. His rectorship would last from December, 1312 until March, 1313. In Paris, he was close to the “Averroistic” circles associated with Peter Abano.
In 1318 he took up the vacant benefice at Padua, having been promised a canonry in 1316 by Pope John XXII. It was in this period that Marsilius served Can Grande of Verona and Matteo Visconti of Milan as a political advisor. They famously sent him to the Count Charles of La Marche to offer him the captaincy of the Ghibelline League. But the mission failed, and with its failure Marsilius returned to Paris and devoted himself to the teaching and practice of medicine.
In 1324 Marsilius completed his sole major work, the Defensor Pacis. Two years later, he was forced to flee to the court of Louis of Bavaria at Nuremberg, as people began to surmise that he was its author. A year later, in 1327, Pope John XXII condemned five propositions from the Defensor Pacis and excommunicated Marsilius declaring him a heretic. Later that year Marsilius would repay the favor and accompany Louis of Bavaria in his bid to seize the imperial crown in Rome. Louis was eventually crowned by Sciarra Colonna as a delegate of the people, and Marsilius joined him in declaring John XXII a heretic and deposing of him, and installing Nicolas V, as the new Pope “by our authority together with the entire clergy and Roman people.” Marsilius was appointed spiritual vicar for the city. But a year later Louis was compelled to withdraw by the people and Marsilius returned with him to Bavaria, where they would both spend the rest of their lives.
A year before he passed away Marsilius composed a short summary of the Defensor Pacis, entitled Defensor Minor. He died in Munich in 1343.