We have all had the experience, on a visit to one of the great temples of Kyoto or Nara, of being shown a scroll, one of the temple's treasures, hanging in a large, deeply recessed alcove.

So dark are these alcoves, even in bright daylight, that we can hardly discern the outlines of the work; all we can do is listen to the explanation of the guide, follow as best we can the all-but invisible brush strokes, and tell ourselves how magnificent a painting it must be.

Yet the combination of that blurred old painting and the dark alcove is one of absolute harmony.

The lack of clarity, far from disturbing us, seems rather to suit the painting perfectly.

For the painting here is nothing more than another delicate surface upon which the faint, frail light can play; it performs precisely the same function as the sand-textured wall.

This is why we attach such importance to age and patina.

A new painting, even one done in ink monochrome or subtle pastels, can quite destroy the shadows of an alcove, unless it is selected with the greatest care.