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. With Angie Hobbs Professor of the Public Understanding of Philosophy at the University of Sheffield Frisbee Sheffield University Lecturer in Classics and Fellow of Downing College, University of Cambridge And Fiona Leigh Associate Professor in the Department of Philosophy at University College London Producer: Simon Tillotson

Melvyn Bragg and guests discuss the British phase of a movement that spread across Europe in the mid-19th and early 20th centuries. Influenced by Charles Baudelaire and by Walter Pater, these Decadents rejected the mainstream Victorian view that art needed a moral purpose, and valued instead the intense sensations art provoked, celebrating art for art’s sake. Oscar Wilde was at its heart, Aubrey Beardsley adorned it with his illustrations and they, with others, provoked moral panic with their supposed degeneracy. After burning brightly, the movement soon lost its energy in Britain yet it has proved influential. The illustration above, by Beardsley, is from the cover of the first edition of The Yellow Book in April 1894. With Neil Sammells Professor of English and Irish Literature and Deputy Vice Chancellor at Bath Spa University Kate Hext Senior Lecturer in English Literature at the University of Exeter And Alex Murray Senior Lecturer in English at Queen’s University, Belfast Producer: Simon Tillotson

Melvyn Bragg and guests discuss William Herschel (1738 – 1822) and his sister Caroline Herschel (1750 – 1848) who were born in Hanover and made their reputation in Britain. William was one of the most eminent astronomers in British history. Although he started life as a musician, as a young man he became interested in studying the night sky. With an extraordinary talent, he constructed telescopes that were able to see further and more clearly than any others at the time. He is most celebrated today for discovering the planet Uranus and detecting what came to be known as infrared radiation. Caroline also became a distinguished astronomer, discovering several comets and collaborating with her brother. With Monica Grady Professor of Planetary and Space Sciences at the Open University Carolin Crawford Institute of Astronomy, Cambridge and an Emeritus Fellow of Emmanuel College, University of Cambridge And Jim Bennett Keeper Emeritus at the Science Museum in London. Studio producer: John Goudie

Melvyn Bragg and guests discuss an early masterpiece of French epic poetry, from the 12th Century. It is a reimagining of Charlemagne’s wars in Spain in the 8th Century in which Roland, his most valiant knight, chooses death before dishonour, guarding the army’s rear from a pagan ambush as it heads back through the Roncesvalles Pass in the Pyrenees. If he wanted to, Roland could blow on his oliphant, his elephant tusk horn, to summon help by calling back Charlemagne's army, but according to his values that would bring shame both on him and on France, and he would rather keep killing pagans until he is the last man standing and the last to die. The image above is taken from an illustration of Charlemagne finding Roland after the Battle of Roncevaux/Roncesvalles, from 'Les Grandes Chroniques de France', c.1460 by Jean Fouquet, Bibliotheque Nationale, Paris, Ms Fr 6465 f.113 With Laura Ashe Professor of English Literature and Fellow in English at Worcester College, University of Oxford Miranda Griffin Assistant Professor of Medieval French at the University of Cambridge and Fellow of Murray Edwards College And Luke Sunderland Professor in the School of Modern Languages and Cultures at Durham University Studio producer: John Goudie

Melvyn Bragg and guests discuss the simple animals which informed Charles Darwin's first book, The Structure and Distribution of Coral Reefs, published in 1842. From corals, Darwin concluded that the Earth changed very slowly and was not fashioned by God. Now coral reefs, which some liken to undersea rainforests, are threatened by human activity, including fishing, pollution and climate change. With Steve Jones Senior Research Fellow in Genetics at University College London Nicola Foster Lecturer in Marine Biology at the University of Plymouth And Gareth Williams Associate Professor in Marine Biology at Bangor University School of Ocean Sciences Producer Simon Tilllotson.