First published in 1651, Leviathan drove important discussions about where kings get their authority to rule and what those kings must, in turn, do for their people. This is known as the "social contract". Thomas Hobbes wrote the book while exiled from his native England following the English Civil War that unseated King Charles I. In the face of England's radical - if temporary - rejection of its monarchy, Hobbes wanted to explain why it was important to have a strong central government, which in his time meant having a sovereign at its head.
Issues of human rights and freedoms always inflame passions, and John Rawls's A Theory of Justice will do the same. Published in 1971, it links the idea of social justice to a basic sense of fairness that recognizes human rights and freedoms. Controversially, though, it also accepts differences in the distribution of goods and services - as long as they benefit the worst off in society.
First available in 1689, John Locke's Two Treatises of Government is considered one of the most important works ever written on the foundations of government. Published anonymously, it argues against the popular idea at the time that monarchs have a God-given right to rule. Instead Locke proposes that sovereignty - supreme authority - ultimately resides with the people.
One of the most influential works of political theory ever written, The Federalist Papers collects 85 essays from 1787 and 1788, when the United States was a new country looking to find its way politically. Thomas Jefferson, author of the country's Declaration of Independence and a future US president, called the work "the best commentary on the principles of government which ever was written".