From the opening sequence, when the narrator announces that the key to understanding the medieval mind lies in the revelation of light, you know that you are a million miles from Kevin Costner’s Robin Hood country. This is a serious investigation of what made the Middle Ages tick: the insight, the fear and above all the faith that produced the great cathedrals and churches, as well as the Inquisition.

The narrator is Christopher Fray-ling, already experienced at presenting the Mask of Tutankhamun for television and here taking us on a guided tour of the medieval mind. That he does so with a minimum of gimmickry is a tribute to the power of television to address serious and difficult issues without losing its audience. It is a pity that so little medieval history is taken beyond the “Medieval Realms” until at lower secondary, because this fascinating and intelligent series cries out for classroom use; as it is, it will be superb preparation for teachers.

Although at one point we have an alarming shot of the Prof looking over his shoulder at us from the cockpit of a helicopter over Chartres cathedral, for the most part Frayling plays a more simple role, introducing us to the real meaning of some of the monuments the Middle Ages left behind. Tourist guides can show you the stained glass windows of Chartres; Frayling shows us the story in the pictures, the significance of their geometry, of their colours (nasty things tend to happen against a red background), and of their arrangement. As he rightly points out, it all makes nonsense of the trite equation that is often made of stained glass windows with modern comic books.

Nevertheless, Frayling is not averse to making modern parallels, some of them quite startling. Francis of Assisi appeared before Pope Innocent III looking like a bag person; massacring heretics in the French town of Beziers was calculated terror, like a bomb in a shopping centre. He hoped that the spirituality of the times, which the series places firmly at centre stage, will speak directly to today’s New Age generation and he’s probably right.

The first programme takes the metaphor of light illuminating the way out of the dark forest to show how the medieval people thought of themselves. We see cathedrals like Chartres and Beauvais as architecture of light, their spires soaring to Heaven, the light flooding through the coloured glass. He does not ignore the more down-to-earth aspects either. Chartres had to be built on a slope to allow for flushing out the debris of the cathedral’s bed and breakfast service for pilgrims.

At times, it is almost as if Frayling is sharing the pilgrims’ reverence for the relics that these great churches boasted: he seems particularly impressed to find the finger of Doubting Thomas a singularly inapt saint to have his relics hawked about even in the 12th Century, I would have thought.

Nowadays we tend to take a more cynical view, not least of the ease with which medieval religion slipped into persecution, which is the focus of the second programme of the series, “The Fires of Faith”. Francis of Assisi strove for godliness through extreme poverty while remaining totally loyal to the church; others rejected the church and were condemned as heretics.

But the programme points out the fine line dividing heretics and saints. St Francis took poverty seriously; when his order grew large and Franciscans began getting servants it was those who tried to follow his example who found themselves condemned as heretics. The men who did the condemning were often the Dominicans of the Inquisition, yet when we meet their founder, St Dominic, he is simply another holy man who wants to preach the gospel. Most striking of all, perhaps, was the little girl St Foix, who was put to death for refusing to worship a statue: now worshippers kneel down in front of her statue in the church that bears her name.

This is high-quality television history, in the tradition of Clark or Bronowski. Frayling has none of the mannerisms or trademarks that either grate or ingratiate in David Attenborough or Michael Wood, but he has an infectious enthusiasm and wonder in his subject. If you can forgive a few ghastly phrases Gothic cathedrals are “machines for worshipping in”, and engaged in “style wars” this is a superb visual treat which manages to find a way into the strange landscape of the medieval mind.