Gazing coolly and a little skeptically from a celebrated self-portrait, the painter himself greets us as we enter “Poussin and Nature: Arcadian Visions” at the Metropolitan Museum of Art.[1] The image, in the collection of the Louvre, is a paradigm of French seventeenth-century painting at its most high-minded and disciplined, all subdued, richly orchestrated non-colors and lucid geometry. Wrapped in an elegant black-gray cloak and framed by stacked canvases, the artist turns to stare at us, as he grasps a portfolio. An inscription on a canvas reads, in Latin, “the effigy of Nicolas Poussin, painter of Les Andelys, at the age of 56, in the Jubilee year of 1650.” Behind the artist, on a picture almost obscured by the canvases piled against it, we glimpse the idealized profile of an allegorical figure of Painting—identified by the all-seeing eye on her diadem—embraced by ...