NOW that the dust of controversy over the cleaning of certain National Gallery pictures has to some extent settled, it is possible to judge some of its results. The ineptitude of much of the criticism should not blind us to its value. Apart from witnessing how greatly some of the owners of the.pictures care about them, both the praise and blame meted out to the National Gallery authorities have revealed a fundamental confusion of thought over the cleaning of pictures-confusion between how a painting looks after treatment, and how its physical condition has been affected. Whether the spectator likes the appearance of a painting is a matter of taste, whereas its physical condition is a matter of fact ; but only too often those who by habit or conviction like to see paintings as in a glass darkly make reckless charges of removal of original glazes, abrasion of surface and so on. That is not to say that criticism of appearance is unjustifiable. Pictures are meant to be looked at, and when all excrescences such as dirt, discoloured varnish and later repaints have been removed, a painting does not necessarily look as the artist meant it to look. Colours may have changed ; there may be breaks in the surface ; cracks may have developed ; the pigment layer may have become more transparent with time, revealing the painter‘s earlier intentions or, in the case of paintings on a dark ground, causing the tone of whole areas to be lowered and so obscuring detail. It therefore becomes a problem for those in charge of paintings to decide what should be done in such cases ; and the decision will range from merely ‘in-painting' with a neutral colour the most obvious and disturbing breaks, to an elaborate tinting out of all blemishes and the use of a toned varnish, or retention of some of the old, to unify the whole. One thing is certain, however, we can never be quite sure how the painter intended his work to look ; and since succeeding generations will have their own opinions on the matter, anything added to or left on a painting in the interests of appearance should be incapable of doing harm, and should be easily and safely removable.