Medieval political philosophy

In a few words, explain the following (around 100 words each):

- What is the source of the secular power or right to rule according to John of salisbury, Dante and Marsilius of padua? 

- In what way does machiavelli break from the teachings of previous political thinkers?

- Compare and contrast Hobbes and Locke on the issues of the state of nature and the social contract. rights