I went to the Met one day in 1997, and I was looking at that painting by Velázquez, of the little girl with the butterfly things in her hair. I thought, That’s an odd color on the forehead, and I realized there was an underpainting, with a vermillion glaze over it. You could see the two layers, and it was magical. The skin color was not like paint, not an exact color, but a combination of layers that formed in your eye.

[…] I was looking for underpainting in every picture in the Uffizi, but it was in Venice that I really saw it. The Accademia puts paintings out on easels, under natural light, and you can get right up close to them and see how some parts were glazed and other parts were not.

— John Currin, LIVES OF THE ARTISTS, by Calvin Tomkins