Artist Pierre Vivant performed a sort of typographical sleight of hand in an Oxfordshire field in 1990. In early summer oilseed rape changes from green to yellow as its flowers open. Vivant cut the words GREEN and YELLOW into the flowering field so that each word bore the color it named. Over the ensuing month, the flowers faded and the field reverted to green while the plants in the areas that Vivant had cut grew and flowered. The end result was the reverse of what you see here: a green field in which the word GREEN is yellow and the word YELLOW is green.