To our medieval forebears the world could appear mysterious, even enchanted. Sightings of green men, dog heads and alien beings were commonplace. The world itself was a book written by God. But as the Middle Ages grew to a close, it became a place to be mastered, even exploited.

Leading authority on the Middle Ages, Professor Robert Bartlett, presents a series which examines the way we thought during medieval times. In the second episode, Bartlett unearths remarkable evidence of the complex passions of Medieval men and women. The Church preached hatred of the flesh, promoted the cult of virginity and condemned woman as the sinful heir to Eve. Yet this was the era that gave birth to the idea of romantic love.

David Attenborough reveals the surprising truth about the cold-blooded lives of reptiles and amphibians. These animals are as dramatic in combat, as colourful in their communication and as tender in their parental care as any other animals. Join giant courting crocodiles, jousting tortoises and bright red sumo-wrestling frogs in their sophisticated, solar-powered lives.

David Attenborough reveals the fascinating lives of snakes, the most misunderstood group of reptiles. A CCTV stakeout of wild rattlesnakes hunting shows, for the first time, what sophisticated predators they truly are. Attenborough is also on the receiving end of a spitting cobra's chemical weapons system, while the surprisingly beautiful and tender side of snakes is displayed in the sinuous courtship of kingsnakes, and the water birth of 15 beautiful yellow anaconda babies.

brilliant mathematicians, whose genius has profoundly affected us, but which tragically drove them insane and eventually led to them all committing suicide. Georg Cantor, the great mathematician whose work proved to be the foundation for much of the 20th-century mathematics. He believed he was God's messenger and was eventually driven insane trying to prove his theories of infinity. Ludwig Boltzmann's struggle to prove the existence of atoms and probability eventually drove him to suicide.

brilliant mathematicians whose genius has profoundly affected us, but which tragically drove them insane and eventually led to them all committing suicide. Kurt Gödel, the introverted confidant of Einstein, proved that there would always be problems which were outside human logic. His life ended in a sanatorium where he starved himself to death. Finally, Alan Turing, the great Bletchley Park code breaker, father of computer science and homosexual, died trying to prove that some things are fundamentally unprovable.