Pure light above, mere earth below

One of the delights of "Light!," the exhibition at Pittsburgh's Carnegie Museum of Art last year, was quite simple: A ray of light shot through a prism, which then diffracted it into a sort of domesticated rainbow that held still to be admired.

We saw the pure hues of the spectrum, a platonic ideal of color. Most of the time we see colors approximated by pigments - reds, for instance, that come up slightly blue, or slightly yellow. Philip Ball's gorgeous new book, "Bright Earth: Art and the Invention of Color" (see review, page 21) explores the chemistry of color and the struggle artists and chemists have had over the centuries to get it right.

It was a set of issues I had been introduced to a few months before the Pittsburgh adventure, when I spent a week studying color in New York. Our little class learned to deconstruct the world around us into hue, value, and intensity. We would mix paints, compare against our subjects, mix and compare again, until we got it right - by which time the light might have changed and we'd have to start anew.

We learned to say violet instead of purple and to see browns and grays as "low-intensity" reds or blues or yellows. Sometimes a banana is just a banana, but its color is never just yellow. Oh, no. Apples? You don't want to get me started.

Emerging into the streets of Soho at noon, we'd see how colors bounce from one wrought-iron façade to another, and why the Impressionists painted shadows in color - blue or lavender or green.

Our first paintings were simple studies involving folded construction paper. But when I looked hard enough at my little composition, I saw light, color, shadow, and reflection come together with all the complexity of a sunrise over mountains.