Written in 1831 and set in 1612, Honoré de Balzac’s curious tale ‘The Unknown Masterpiece’ could be a fable for the avant-garde of 1917 or the participatory art of our own century. A young Nicolas Poussin meets two older painters: the cynical Porbus and the mysterious Frenhofer, who has been working for ten years in a futile effort to capture the glow of a young woman’s flesh. At length, with Poussin’s mistress as his model, the aged artist produces a composition overworked to the point of catastrophe, ‘colours daubed one on top of the other and contained by a mass of strange lines forming a wall of paint’. Only a tiny, delicate foot emerges from the chaos. Although none of the three artists knows it, the painting is a perfectly imperfect expression of the principle that ruined, botched or otherwise incomplete works of art are frequently the most prized.

‘The Unknown Masterpiece’ is mentioned more than once in Unfinished, a hefty catalogue of partial or imperfect works produced to accompany an exhibition at the Met. As the author-curators note early on, theirs is not a study of ruin, whether arrived at violently or by long, melancholy decay.