It's been the color of power, of passion, of courage and danger. As far back as history can record, red has taken on special meaning and the red dye cochineal, the most potent natural red dye in the world, was at one time such a luxury that it only trailed silver as New Spain's most valuable export. Cochineal dyed cloth provided the fabric for royal robes and the uniform's of the world's fiercest fighters, while artists like Rembrandt and Rubens used cochineal in their paintings. Today on the Exchange we explore the history of the color red, the dye cochineal and how one color could mean so much to so many. Laura's guest is Amy Butler Greenfield, author of "A Perfect Red: Empire, Espionage, and the Quest for the Color of Desire".