In ancient Greece, thousands of people flocked each year to join the religious rites known as the Eleusinian Mysteries. Based on the cult of the goddess of fertility Demeter and her daughter Persephone, the Mysteries were for many a profoundly moving and life-changing experience. People from all over the Greek world and beyond travelled to Eleusis for at least 800 years and the ceremonies remained a highlight of the Athenian calendar throughout that time. But what really went on in the great hall of the sanctuary at Eleusis? Why did the organisers deem it necessary to issue a strict injunction against divulging what actually took place - and what happened to some of those who broke that rule?

These are some of the questions Bridget Kendall discusses with Christy Constantakopoulou, professor in ancient history and classics at Birkbeck College, London; Esther Eidinow, professor of ancient history at Bristol University; Dr. Philippe Michel Matthey who lectures about ancient religions at Geneva University; and Dr. Julietta Steinhauer, a lecturer in Hellenistic history at University College, London.

[Image: Detail from a vessel showing a scene of the Eleusis cult with Triptolemus in a winged chariot and Demeter, c.460 BC. Credit DeAgostini/Getty Images]