On a spectacular journey through Renaissance Italy, Andrew Graham-Dixon searches for the shadowy figure who wrote one of the most important books on art and looks at some dazzling works, including masterpieces of the early Renaissance by Giotto, Masaccio and Donatello. Giorgio Vasari was the grandaddy of all art critics, travelling Italy in the 16th century for his definitive Lives of the Artists. It was a time of miracles that he named 'the Renaissance'.