When conservators clean a centuries-old painting, they confront a question no chemistry can settle: what, exactly, are they restoring it to? Strip away the yellowed varnish and grime, and colors leap back to a brilliance the artist surely intended. Yet the same solvents can lift the delicate glazes the painter laid down last, the finishing touches that gave a face its final expression. I have stood in studios where two respected specialists, examining the identical canvas, disagreed flatly: one saw dirt to be removed, the other saw the artist's own hand. The public tends to imagine restoration as a return to an original, fixed state, as though the painting were a photograph waiting under decades of soot. But there is no single original. A canvas begins changing the moment it dries; pigments shift, oils darken, and the artist's intention may itself have evolved between the first brushstroke and the last. The conservator, then, is not a time machine but an interpreter, making arguments in the language of solvents and swabs. Every cleaning is a reading, and like all readings, it is also, unavoidably, a choice.