Devil's food, indeed.
Chocolate, made from the bean of the South American cocoa plant, was firstly and for many generations only had as a thick, bitter beverage. Aztec nobles always took some before going to bed with a woman, and Montezuma supposedly had 50 cups a day for exactly that reason. After all, he had a harem of 600. In Mayan culture a night in a brothel cost a handful of cocoa beans.
I believe it was the Incans who decreed that because of its power to incite lust, women were not permitted have any. Go figure.
When the Spanish observed the wild orgies that went on during the cocoa harvests, they quite naturally brought it back to an unsuspecting Europe, which immediately became enamored of chocolate.
Within a few decades, French monks were forbidden to taste chocolate, the Spanish Inquisition prosecuted several women for drinking it (the implications were that they were in league with the Devil, though the Inquisitors, who also drank the stuff, were presumably not), Spanish American women made scandals by drinking it in church, and all sorts of delicious trouble came of the little brown beans. Not too long afterward, Casanova made use of it as well, and swore by its effects.
Today chocolate is as popular as ever, and comes in more shapes and forms than the Aztecs ever dreamed. It remains a symbol of romance, and a strong social (as opposed to medical) aphrodisiac.
Science has discovered a bevy of good things intrinsic to chocolate: calcium, phosphorus, potassium, riboflavin, thiamine, and vitamin A. It also has a minute amount of caffeine and a substance called phenylethylamine (PEA for short). PEA is an endorphin, a natural amphetamine which is also generated by the brain of someone falling in love, meaning that chocolate emphasizes and may even cause that marvelous sensation. In addition to all this is the recent revelation that cocoa beans house a cannabinoid, one of the "active" ingredients in marijuana.
Though I adore dense, powerful chocolate creations and make them whenever I have the time, someone will occasionally comment that the confection features "too much chocolate." I believe the phrase is meaningless.