The English philosopher and physician John Locke (1632 - 1704) is widely regarded as one of the most influential of Enlightenment thinkers. His work had a significant effect on the development of epistemology and political philosophy. The Second Treatise on Civil Government places sovereignty in the hands of the people, as Locke's fundamental argument is that people are equal and invested with natural rights in a state of nature in which they live free from outside rule.

Often considered the foundation of political liberalism, John Locke's Two Treatises of Government was first published anonymously in 1689, in the wake of England's Glorious Revolution. In The First Treatise of Government, Locke refutes the idea of divine monarchy, while The Second Treatise of Government articulates Locke's philosophy of government, which he based upon his theories of natural rights and the social contract.

Published in 1651, Leviathan is considered to be one of the most important works of political philosophy and a major contribution to the modern idea of central government. In the mid-17th century, England was going through a turbulent time of change and unrest, which likely shaped Hobbes' ideas on strong government. Thomas Hobbes established the social contract theory. He believed that self-government did not create the ideal state due to the human tendency to be self-serving, something he believed would eventually lead to chaos.

John Locke and his works - particularly An Essay Concerning Human Understanding - are regularly and rightly presented as foundations for the Age of Enlightenment. His primary epistemological message - that the mind at birth is a blank sheet waiting to be filled by the experiences of the senses - complemented his primary political message: that human beings are free and equal and have the right to envision, create and direct the governments that rule them and the societies within which they live.

Discourse on the Origin and Basis of Inequality Among Men by the philosopher Jean-Jacques Rousseau was originally written for an essay competition run by the Dijon Academy of Arts and Sciences in 1754. The question was, "What is the origin of inequality among men, and is it authorized by the natural law?" Rousseau's text is divided into four main parts: a dedication, preface, an extended inquiry into the nature of the individual, and another inquiry into the evolution of the human species within society.

The foundation for all modern economic thought and political economy, The Wealth of Nations is the magnum opus of Scottish economist Adam Smith, who introduces the world to the very idea of economics and capitalism in the modern sense of the words.

Man is born free, and everywhere he is in chains. In The Social Contract, Rousseau explores the concept of freedom and the political structures that may enable people to acquire it. He argues that the sovereign power of a state lies not in any one ruler but in the will of the general population. Rousseau argues that the ideal state would be a direct democracy where executive decision making is carried out by citizens who meet in assembly, as they would in the ancient city-state of Athens.

From the moment of its publication in 1748, The Spirit of the Laws proved to be a controversial work provoking widespread interest. Within three years it had been translated into various European languages - and was swiftly added to the List of Prohibited Books by the Roman Catholic Church. It is a remarkable book, a potpourri of observations and comments ranging far and wide over the social activities of mankind and it exerted a great influence on political leaders in the following decades.

Though it first aroused anger and controversy rather than admiration and acceptance, A Theologico-Political Treatise was a landmark in the analysis of theology (with particular reference to the Bible and its Jewish and Christian interpretations) and its relationship to philosophy and politics. Spinoza’s scholarly analysis, based on careful study, demonstrated that the Bible was composed by many writers over the centuries - and that even the Pentateuch, the first five books, were not the work of Moses, as was generally assumed at the time.

The title Politics literally means ‘the things concerning the city’. Here, Aristotle considers the important role that politics plays in the life of the community and its contribution to harmonious and virtuous existence. It is divided into eight books and was a cornerstone in political philosophy for centuries despite certain features - including attitudes towards slaves and women - clearly placing its conclusions and advice within the confines of Athenian society of the fourth century BCE.

The Republic poses questions that endure: What is justice? What form of community fosters the best possible life for human beings? What is the nature and destiny of the soul? What form of education provides the best leaders for a good republic? What are the various forms of poetry and the other arts, and which ones should be fostered and which ones should be discouraged? How does knowing differ from believing?

In On the Genealogy of Morals, subtitled "A Polemic", Nietzsche furthers his pursuit of a clarity that is less tainted by imposed prejudices. He looks at the way attitudes towards 'morality' evolved and the way congenital ideas of morality were heavily colored by the Judaic and Christian traditions.

Intended to be a defense of the Christian religion, Pensées is a penetrating collection of thoughts on faith, reason, and theology. Unfinished at the time of Pascal's death, the book consists of philosophical fragments on the "wretchedness" of man and the controversial schisms of the church at the time. It includes the philosopher's infamous wager encouraging belief over agnosticism, as well as his thoughts on numerous other topics. Endlessly quotable, Pensées overflows with pearls of wisdom, each elusive sentence pregnant with a universe of thought.

In 1831, Alexis de Tocqueville, a young French aristocrat and civil servant, made a nine-month journey through the eastern United States. The result was Democracy in America, a monumental study of the strengths and weaknesses of the nation’s evolving politics. His insightful work has become one of the most influential political texts ever written on America.

Immanuel Kant’s Critique of Pure Reason can lay claim to being the most important single work of modern philosophy, a work whose methodology, if not necessarily always its conclusions, has had a profound influence on almost all subsequent philosophical discourse. In this work Kant addresses, in a groundbreaking elucidation of the nature of reason, the age-old question of philosophy: “How do we know what we know?” and the limits of what it is that we can know with certainty.