Alastair Sooke focuses on the reasons behind the revolution that gave birth to classical Greek art. He travels in Sicily to the Valley of the Temples in Agrigento before heading to the island of Mozia to see the Charioteer, which was unearthed in 1979. He also marvels at the athletic bodies of the Riace bronzes - warriors dragged from the seabed - as he asks how the Greeks became so good so quickly