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.

In this classic work, Leo Strauss examines the problem of natural right and argues that there is a firm foundation in reality for the distinction between right and wrong in ethics and politics. On the centenary of Strauss's birth, and the fiftieth anniversary of the Walgreen Lectures which spawned the work, Natural Right and History remains as controversial and essential as ever.

Beyond the rehashed clichés, this book inspires us to rediscover Diogenes' philosophical legacy—whether it be the challenge to the established order, the detachment from materialism, the choice of a return to nature, or the formulation of a cosmopolitan ideal strongly rooted in the belief that virtue is better revealed in action than in theory.

In The Conquest of Bread, first published in 1892, Kropotkin set out his ideas on how his heightened idealism could work. It was all the more extraordinary because he was born into an aristocratic land-owning family - with some 1,200 male serfs - though from his student years his liberal views and his fixation on the need for social change saw him take a revolutionary path. This led rapidly to decades of exile. It is a passionate, even a fierce polemic for dramatic social change.

Johann Gottlieb Fichte (1762-1814) was the forerunner of the post-Kantian idealists and remains one of the most important figures in German philosophy. Throughout his career, Fichte published, in addition to his systematic or "scientific" treatises, the best known of which is the "Foundation of the Entire Wissenchaftslehre (1794-5), a series of works directed at the general public.

Underlain by an acute sense of ethics, this provided the basis for his strongly declared, wide-ranging views on many subjects: prohibition of cock-fighting, liberty of the press, universal suffrage, the removal of religious tests for office and even hunting. All were radical ideas for his time. He also proposed the decriminalisation of homosexuality, though even he did not dare to publish his essay on this subject during his lifetime. But An Introduction to the Principles of Morals and Legislation was his major work.

From the perspective of an unbeliever, Fear and Trembling explores the paradox of faith, the nature of Christianity, and the complexity of human emotion. Kierkegaard examines the biblical story of Abraham, who was instructed to sacrifice his son Isaac, and forces us to consider Abraham's state of mind. What drove Abraham, and what made him carry out such an absurd and extreme request from God? Kierkegaard argues that Abraham's agreement to sacrifice Isaac, and his suspension of reason, elevated him to the highest level of faith.

First published in 1936, Keynes’ ideas had evolved during the difficulties following World War 1 in Europe, and the US crash and the Depression of the 1920s-'30s and the misery of mass unemployment. He deplored the situation where a few individuals or companies stored massive wealth while vast numbers experienced poverty and insecurity (his alarm bells ring today!) and sought to promote initiatives where governments could intervene with social projects to keep money fluctuating.

William James was one of the most influential figures in 19th-century American philosophy and psychology. His Pragmatism is a set of lectures that he gave in 1906-07 in answer to the enduring debate between empiricism and rationalism. Shifting between them, he proposed pragmatism as a method, the idea being that the value of any truth is dependent upon its utility–upon its practical and experiential consequences.

Thomas Mann's last great novel, first published in 1947 and now newly rendered into English by acclaimed translator John E. Woods, is a modern reworking of the Faust legend, in which Germany sells its soul to the Devil. Mann's protagonist, the composer Adrian Leverkühn, is the flower of German culture, a brilliant, isolated, overreaching figure, his radical new music a breakneck game played by art at the very edge of impossibility. In return for twenty-four years of unparalleled musical accomplishment, he bargains away his soul—and the ability to love his fellow man.

The Economic Consequences of the Peace (1919) was one of the most important documents to come out of World War I – specifically the period of the Armistice and the subsequent settlement negotiations. And, a century on, it remains of particular relevance to our times – an uncompromising and forthright analysis of how international diplomacy can be suffused by personalities, prejudices, personal ambition and outright, uncontrolled feelings of revenge.

John Locke (1632-1704) was a product of his troubled times: he lived through the English Civil War, the Interregnum, the Restoration, Monmouth’s Rebellion, the Bloody Assizes and the Glorious Revolution. His empirical thinking was very much directed at finding rational solutions to the root causes of those troubles.

The four books of the Summa contra Gentiles were written by Thomas Aquinas between 1259-1265, before the considerably larger and more influential, Summa Theologica. The purpose of each work was different. Whereas the Summa Theologica addressed the faithful, especially theology students, the intention of the Summa Contra Gentiles (Systematic Exposition Against Non-Christians) was to speak to a non-aligned and even hostile audience. To that purpose, Aquinas presented arguments ‘refuting specific beliefs or heresies.'

This remarkable account has had an enduring influence on social and economic studies and has remained in print since its first English publication in 1885. It was written, in German, by a youthful Friedrich Engels, the son of a German industrialist, who was already concerned - even angered - by the conditions he saw inflicted on the working classes as the Industrial Revolution gathered momentum. His first visit to England (1842-44) and what he saw there with his own eyes fuelled his concerns and prompted him to make this formal study.

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.