Melvyn Bragg and guests discuss Plato's account of the once great island of Atlantis out to the west, beyond the world known to his fellow Athenians, and why it disappeared many thousands of years before his time. There are no sources for this story other than Plato, and he tells it across two of his works, the Timaeus and the Critias, tantalizing his readers with evidence that it is true and clues that it is a fantasy. Atlantis, for Plato, is a way to explore what an ideal republic really is, and whether Athens could be (or ever was) one; to European travellers in the Renaissance, though, his story reflected their own encounters with distant lands, previously unknown to them, spurring generations of explorers to scour the oceans and in the hope of finding a lost world.The image above is from an engraving of the legendary island of Atlantis after a description by Athanasius Kircher (1602-1680).With Edith Hall Professor of Classics at Durham UniversityChristopher Gill Emeritus Professor of Ancient Thought at the University of ExeterAndAngie Hobbs Professor of the Public Understanding of Philosophy at the University of SheffieldProducer: Simon Tillotson

Melvyn Bragg and guests discuss ideas of Georg Wilhelm Friedrich Hegel (1770 - 1831) on history. Hegel, one of the most influential of the modern philosophers, described history as the progress in the consciousness of freedom, asking whether we enjoy more freedom now than those who came before us. To explore this, he looked into the past to identify periods when freedom was moving from the one to the few to the all, arguing that once we understand the true nature of freedom we reach an endpoint in understanding. That end of history, as it's known, describes an understanding of freedom so far progressed, so profound, that it cannot be extended or deepened even if it can be lost.WithSally Sedgwick Professor and Chair of Philosophy at Boston UniversityRobert Stern Professor of Philosophy at the University of SheffieldAnd Stephen Houlgate Professor of Philosophy at the University of WarwickProducer: Simon Tillotson

Melvyn Bragg and guests discuss the Czech educator Jan Amos Komenský (1592-1670) known throughout Europe in his lifetime under the Latin version of his name, Comenius. A Protestant and member of the Unity of Brethren, he lived much of his life in exile, expelled from his homeland under the Catholic Counter-Reformation, and he wanted to address the deep antagonisms underlying the wars that were devastating Europe especially The Thirty Years War (1618-1648). A major part of his plan was Universal Education, in which everyone could learn about everything, and better understand each other and so tolerate their religious differences and live side by side. His ideas were to have a lasting influence on education, even though the peace that followed the Thirty Years War only entrenched the changes in his homeland that made his life there impossible.The image above is from a portrait of Comenius by Jürgen Ovens, 1650 - 1670, painted while he was living in Amsterdam and held in the RikjsmuseumWithVladimir Urbanek Senior Researcher in the Department of Comenius Studies and Early Modern Intellectual History at the Institute of Philosophy of the Czech Academy of SciencesSuzanna Ivanic Lecturer in Early Modern European History at the University of KentAndHoward Hotson Professor of Early Modern Intellectual History at the University of Oxford and Fellow of St Anne’s CollegeProducer: Simon Tillotson

Melvyn Bragg and guests discuss the idea of charismatic authority developed by Max Weber (1864-1920) to explain why people welcome some as their legitimate rulers and follow them loyally, for better or worse, while following others only dutifully or grudgingly. Weber was fascinated by those such as Napoleon (above) and Washington who achieved power not by right, as with traditional monarchs, or by law as with the bureaucratic world around him in Germany, but by revolution or insurrection. Drawing on the experience of religious figures, he contended that these leaders, often outsiders, needed to be seen as exceptional, heroic and even miraculous to command loyalty, and could stay in power for as long as the people were enthralled and the miracles they had promised kept coming. After the Second World War, Weber's idea attracted new attention as a way of understanding why some reviled leaders once had mass support and, with the arrival of television, why some politicians were more engaging and influential on screen than others. With Linda Woodhead The FD Maurice Professor and Head of the Department of Theology and Religious Studies at King's College LondonDavid Bell The Lapidus Professor in the Department of History at Princeton UniversityAndTom Wright Reader in Rhetoric at the University of SussexProducer: Simon Tillotson

Melvyn Bragg and guests discuss the ancient Sanskrit text the Arthashastra, regarded as one of the major works of Indian literature. Written in the style of a scientific treatise, it provides rulers with a guide on how to govern their territory and sets out what the structure, economic policy and foreign affairs of the ideal state should be. According to legend, it was written by Chanakya, a political advisor to the ruler Chandragupta Maurya (reigned 321 – 297 BC) who founded the Mauryan Empire, the first great Empire in the Indian subcontinent. As the Arthashastra asserts that a ruler should pursue his goals ruthlessly by whatever means is required, it has been compared with the 16th-century work The Prince by Machiavelli. Today, it is widely viewed as presenting a sophisticated and refined analysis of the nature, dynamics and challenges of rulership, and scholars value it partly because it undermines colonial stereotypes of what early South Asian society was like. WithJessica Frazier Lecturer in the Study of Religion at the University of Oxford and a Fellow of the Oxford Centre for Hindu StudiesJames Hegarty Professor of Sanskrit and Indian Religions at Cardiff University And Deven Patel Associate Professor of South Asia Studies at the University of PennsylvaniaProducer: Simon Tillotson

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Melvyn Bragg and guests discuss one of the most celebrated thinkers of the twentieth century. Walter Benjamin (1892-1940) was a German Jewish philosopher, critic, historian, an investigator of culture, a maker of radio programmes and more. Notably, in his Arcades Project, he looked into the past of Paris to understand the modern age and, in The Work of Art in the Age of Mechanical Reproduction, examined how the new media of film and photography enabled art to be politicised, and politics to become a form of art. The rise of the Nazis in Germany forced him into exile, and he worked in Paris in dread of what was to come; when his escape from France in 1940 was blocked at the Spanish border, he took his own life. With Esther Leslie Professor of Political Aesthetics at Birkbeck, University of LondonKevin McLaughlin Dean of the Faculty and Professor of English, Comparative Literature and German Studies at Brown UniversityAndCarolin Duttlinger Professor of German Literature and Culture at the University of OxfordProducer: Simon Tillotson

Melvyn Bragg and guests discuss one of Plato's most striking dialogues, in which he addresses the real nature of power and freedom, and the relationship between pleasure and true self-interest. As he tests these ideas, Plato creates powerful speeches, notably from Callicles who claims that laws of nature trump man-made laws, that might is right, and that rules are made by weak people to constrain the strong in defiance of what is natural and proper. Gorgias is arguably the most personal of all of Plato's dialogues, with its hints of a simmering fury at the system in Athens that put his mentor Socrates to death, and where rhetoric held too much sway over people. WithAngie Hobbs Professor of the Public Understanding of Philosophy at the University of SheffieldFrisbee Sheffield University Lecturer in Classics and Fellow of Downing College, University of CambridgeAndFiona Leigh Associate Professor in the Department of Philosophy at University College LondonProducer: Simon Tillotson

Melvyn Bragg and guests discuss the author and philosopher Iris Murdoch (1919 - 1999). In her lifetime she was most celebrated for her novels such as The Bell and The Black Prince, but these are now sharing the spotlight with her philosophy. Responding to the horrors of the Second World War, she argued that morality was not subjective or a matter of taste, as many of her contemporaries held, but was objective, and good was a fact we could recognize. To tell good from bad, though, we would need to see the world as it really is, not as we want to see it, and her novels are full of characters who are not yet enlightened enough to do that.WithAnil Gomes Fellow and Tutor in Philosophy at Trinity College, University of OxfordAnne Rowe Visiting Professor at the University of Chichester and Emeritus Research Fellow with the Iris Murdoch Archive Project at Kingston UniversityAndMiles Leeson Director of the Iris Murdoch Research Centre and Reader in English Literature at the University of ChichesterProducer: Simon Tillotson

Melvyn Bragg and guests discuss the insight into our relationship with the world that Immanuel Kant (1724-1804) shared in his book The Critique of Pure Reason in 1781. It was as revolutionary, in his view, as when the Polish astronomer Copernicus realised that Earth revolves around the Sun rather than the Sun around Earth. Kant's was an insight into how we understand the world around us, arguing that we can never know the world as it is, but only through the structures of our minds which shape that understanding. This idea, that the world depends on us even though we do not create it, has been one of Kant’s greatest contributions to philosophy and influences debates to this day. The image above is a portrait of Immanuel Kant by Friedrich Wilhelm SpringerWith Fiona Hughes Senior Lecturer in Philosophy at the University of EssexAnil Gomes Associate Professor and Fellow and Tutor in Philosophy at Trinity College, OxfordAnd John Callanan Senior Lecturer in Philosophy at King’s College LondonProducer: Simon Tillotson