Today is national coffee day. More than 400 billion cups of coffee are consumed each year. It is now a world commodity that is second only to oil. According to legend, a sixth-century Ethiopian goatherd named Kaldi discovered his goats frolicking from one coffee shrub to another. He realized the coffee berries had a stimulating effect, and he began to experiment with the seeds. A century later, brewed coffee emerged in Arabia and the popularity of coffee grew at an exponential rate.