Dr Jonathan Miller, polymath, renaissance chap and intellectual, has returned to a favourite subject - that of reflection - in creating the Mirror Image exhibition at the National Gallery. It is a collection of pictures from the great galleries of Europe and the United States and develops ideas of vision and perception.

Dr Miller calls Mirror Image “a modest and provocative essay” and hopes it will make people “look and see differently”, defining “looking” as the act and “seeing” as the experience.

The observation of pictures is accompanied by personal observations of observers: a cat looking into a puddle and deciding not to walk on it, or his 18-month-old granddaughter discovering herself in a mirror. Dr Miller also explores surface, depth, reverse optics and illusion.

In a section called “virtual surfaces” you can contemplate van Eyck’s “Arnolfini Portrait”, in which a pregnant wife and her husband are depicted conventionally in the foreground and reflected in a convex mirror at the back. The reflection is distorted not only by the complex shape of the mirror but also by the mirror reflecting light from the window at the side of the couple.

Dr Miller points out that the mirror turns our attention in the opposite direction to that of the scene represented and that somehow we are persuaded voluntarily to supply the glass in the painting, to “see” the medium that supports the view. How does flat oil paint create this illusion?

Many of the paintings show windows, window glass or open windows, either revealing the outside or reflecting back an angled version of the room.

This idea is examined further with the distinctions made by framings - doors, other paintings, windows, water - within the pictures, which Dr Miller describes as the sense of an annexe.

Surrealists have enjoyed playing games with mirrors. In Magritte’s “Portrait of Edward James”, we see the back of a man looking into a mirror which shows his reflection as an exact replica of what we see, the back of the man. The book on the mantlepiece is the right way round and to the viewer this presents a clear impossibility even though we understand that the artwork is itself a fabrication.

Dr Miller says that people and chimpanzees “appear to be the only animals capable of identifying themselves in their reflection”, and says the mirror has complex metaphorical significance, epitomising both the vice of vanity and the virtue of prudent self-knowledge.

Sixth-form art classes will find plenty to occupy them.

Mirror Image runs until December 13 at the National Gallery, 5-6 Pall Mall East, London SW1Y 5BA. Admission Pounds 1 per person for school groups of up to 20, including a recorded commentary by Dr Miller. School bookings on 0171 747 2424