Buff

Ribbons of green, blue, pink, tan, and orange sweep down the canvas in this piece called "Buff," painted by British artist Bridget Riley in 1966. The curving shapes seem to twist and ripple even though they never actually move, an effect that can make your eyes feel almost dizzy. Riley was a central name in Op Art, a movement of the 1960s built around optical tricks and the surprising ways our eyes read color and form.

Rhythm was at the heart of everything Riley made. She studied how repeating curves and thoughtfully paired colors could give a flat surface a pulse and a sense of flow. Every shift in tone here is planned with real care, so the whole composition seems to breathe while sitting perfectly still.

One quirky fact about Riley is that she rarely picked up the brush for these large works herself. She mapped out each line and color with exacting detail, then handed the plans to trained assistants who did the painting, a bit like a composer trusting musicians to play the score. The finished result is sharp, clean, and endlessly playful for the eye.