Marslius begins his account of secular authority by articulating what he believes are the fundamentals of human nature. Uncontroversially he states that “that all human beings not deformed or otherwise impeded naturally desire a sufficient life, and avoid or flee what is harmful thereto.” In simple terms, we pursue what is advantageous to us and avoid that which is not if we can.

However, unlike other animals, humans are not content to live in the wild. We do not only long for necessities such as food, water and shelter. Humans also long for luxuries, companionship, and entertainment. To achieve our desires an innumerable amount of skills are required, too many for one person to possibly master. The comforts we long for “cannot be exercised except by a large number of people through their association with one another, it was necessary for human beings to assemble together to obtain advantage.” For Marsilius, the division of labour is a natural and essential component of human existence. It takes multiple people to make even the simplest loaf of bread.

We unite together and form political communities to serve our own best interests. We benefit greatly from the division of labour and by exchanging goods and services with one another. Through our variety of talents and skills, we all can serve one another. However, we are not perfect by any stretch. Marsilius writes, “Everyone is prone to pursue one’s own advantage.” Marsilius believes that, by their nature, all people are self‐​interested; this is the unavoidable condition of humanity. This was a radical position at the time. During the medieval ages pursuing one’s own private advantage was often viewed as a vice which was indicative of man’s fallen nature. The bible was invoked when condemning self‐​interested behaviour, like the verse stating that it was “easier for a camel to go through the eye of a needle than for a rich man to enter the kingdom of God.” Marsilius did not agree with this view and instead believed that as long as we are not harming others, we are free to pursue our own advantage as much as we like.

But this will inevitably lead to conflict when people overstep boundaries or pursue their own interests at the expense of another person. To solve this, we must have law, the primary function of secular power and which promotes peace. Without strife or conflict, we may pursue our own personal advantage, as long as this pursuit does not harm or hinder others.

Notice that Marsilius’s account of secular power is based around the sufficient life “which no one can obtain without peace and tranquillity.” According to Marsilius, the state does not exist to promote moral virtue or the heavenly salvation of its citizens as commonly expressed by his contemporaries. Instead, the state ought to pursue secular goals such as promoting prosperity and peace, while leaving the moral development of citizens to the non‐​coercive spiritual powers.