As part of BBC Four's Medieval Season, Professor Robert Bartlett (pictured) - one of the world's leading medievalists - takes a trip into the medieval psyche in a new, four-part series, Inside The Medieval Mind. Each hour-long episode - Knowledge, Sex, Belief and Power - focuses on a different aspect of medieval life.

The medieval world was full of marvels and, in tonight's episode, Professor Bartlett unearths how medieval men and women understood the world - and how that knowledge came to be transformed.

Medieval science was not nonsense: it was known that the world was round, for example. However, for medieval man, it was possible to attribute both a natural and a divine cause to a single event - an eclipse could be caused by the movement of the planets and be a sign from God.

In a medieval chained library (books were so rare in the Middle Ages that they would be chained together so that no one could steal them) Robert explains how, for hundreds of years, learning remained (almost literally) in the hands of monks. But that monopoly was to be challenged with the discovery of the classical learning of Aristotle, and of Arabic science, in the great libraries of Spain, seized by Christian soldiers in the 11th and 12th centuries. He also looks at the work of theologians including Thomas Aquinas, and scientists such as Roger Bacon, who were pushing back the frontiers of knowledge in favour of a more evidence-based analysis of the world.

Incredibly, the medieval times were also a period of great discovery; Marco Polo and other travellers returned with amazing tales of the East, signalling the beginning of the end for the established medieval world view. As the Middle Ages drew to a close, Robert discovers that the world had become a place not to be contemplated, but mastered, even exploited.

Preview courtesy of BBC