In Knowledge, Professor Bartlett explores the way medieval man understood the world as a place of mystery, even enchantment - a book written by God.

The medieval world was full of marvels as revealed through medieval sources. He unearths records of strange sightings of fish men caught off the coast of Suffolk, or green men in Essex. Travelling to Hereford Cathedral he decodes the Mappa Mundi, with its three continents (Europe, Africa and Asia) and its strange beasts thought to exist on the periphery of the earth: hermaphrodites, unicorns, men with the heads of dogs.

Medieval science was not nonsense: it was known that the world was round, for example. But 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 Robert explains how for hundreds of years learning remained (almost literally) in the hands of monks and how the monopoly was 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.

Though theologians like Thomas Aquinas worked hard to reconcile classical learning with Christian teaching, scientists such as Roger Bacon pushed back the frontiers of knowledge in favour of a more evidence-based analysis of the world.

Marco Polo and other travellers returned with amazing tales of the East, signalling the beginning of the end for the established medieval world view. They found not dog-heads but great civilisations.

When Columbus sailed off to find a new route to the East he was helped by all the new technology of the time – better sailing ships, gunpowder, compasses. As the Middle Ages grew to a close, the world had become a place not to be contemplated, but mastered, even exploited.