As far back as 2700 B.C.. Chinese Emperor Shen Nung regularly imbibed hot brewed tea. Coffee was regarded by some Westerners as "the devil's brew" until the late sixteenth century, when Pope Clement VIII tasted it and gave it his blessing. Caffeine is the most popular drug in the world. Coffee consumption in the U.S. has actually been steadily declining since the l960s. The main sources of caffeine are, coffee beans, tea leaves, cocoa pods and cola nuts. Another popular source is mate' leaves. Pure caffeine is a bitter-tasting white powder that resembles cornstarch. Drip coffee contains more caffeine than perc