The point of Richter though is less his subjects than his stylistic variety. Underlying much of his representational work is photography. Many of his portraits are paintings of photographs — family snapshots or images torn from magazines. The same is true of his series depicting candles or skulls, landscapes or buildings: by treating them at one remove he turns them into still-lifes. Rather than bland reproduction though he blurs the paint, subtly softening the focus in a signature version of sfumato. The effect can be unnerving, as if the subject instead of being still is in the first twitch of movement or that the air surrounding it has suddenly thickened so that the picture crackles and coalesces like radio interference.

This fascination with the picture surface is even more apparent in his abstracts. Unusually he has painted them since the 1960s, for as long as he has painted his more realist work, the two strands running concurrently. His interest is not in colour, since he has produced large numbers of works solely in grey, but in the artist's mark itself. He has photographed a single brushstroke and expanded it to 20 feet long as well as painting sinuous lines where the colour changes as the eye follows each path.

It would be wrong though to see Richter as either an unduly technical artist or as an unreflective one. For all his diversity and interest in pattern-making the thing that inevitably defines his work is old-fashioned beauty.

One of Richter's most evocative portraits is Reader of 1994, showing a simply-dressed girl intent on a magazine. It is a pared-down image that in its stillness recalls the work of Vermeer, who is the subject of a special exhibition at the Fitzwilliam Museum in Cambridge — Vermeer's Women: Secrets and Silence. There are four of his paintings among the more than 30 Golden Age works on show and if this seems few it is worth remembering that it represents more than ten per cent of his known output (there are only 34 attested paintings in existence). Added to that the museum has somehow managed to borrow the Louvre's wonderful The Lacemaker (1669-70), the first time this picture has been seen in Britain. It is an extraordinary coup.