Chocolate comes from the cacao beans of the cacao tree. The scientific name for this tree is "theobroma cacao" with theobroma meaning "food of the gods." Chocolate was introduced to the Western world by Hernan Cortes, the famous Spanish Conquistador, who conquered the Aztecs in 1519-21. You can read about the conquest in the gripping book, The Conquest of New Spain by Bernal Diaz-another conquistador who participated in it.
Drinking chocolate was a favorite of the Mayans and Aztecs. Ceremonial bowls with which to drink chocolate have been found in western Honduras dating back to 1600 BC. The cacao beans were a commodity which were also used as a kind of money (along with red spiny oyster shell, obsidian, jade, salt and cloth) by many Indians of MesoAmerica-particularly the Mayans. The use of cacao beans as a kind of money did not end with the Spanish conquest of MesoAmerica. They were considered such a valuable commodity that in the 1540s Nicaraguan prostitutes charged 10 cacao beans for their services.
According to Cortes, chocolate was called xocoatl by the Aztecs (the 'x' is pronounced 'sh'). Another possible derivation of the word is that it is a combination of the Mayan 'chocol' and the Aztec/Nahuatl word 'atl'-meaning water. It was a favorite drink of the Aztec nobility and made by drying cacao beans, roasting them over a fire, pounding them to a paste and mixing them with water. Other spices including chili, pimento and vanilla were often added to it. It was thought to have both medicinal properties and to be an aphrodisiac. There was a famous gathering of Aztec wise men and poets about 1490 when they met to discuss the true meaning of poetry. It took place at the house of lord Tecayehuatzin, prince of Huexotzinco. The poets and wise men lay on mats and were served tobacco and foaming mugs of chocolate by servants while they discussed the true meaning of flowers-and-song which is what the Aztecs called poetry.
There was subsequently a considerable trade in chocolate paste to Italy and Flanders by the early 1600s. It became much more popular in Europe with the introduction of sugar. In 1650 drinking chocolate was popular in England and the first chocolate house opened in London in 1657. Drinking chocolate became popular in Europe over the next three hundred years but it did not become a favorite in a solid form until the nineteenth century. It is a commodity, like many, with unpleasant associations to the history of its production. When it became popular in Europe many European nations began growing the cacao beans in their own tropical colonies and many Indian and African slaves were used on cacao plantations.
The addition of milk, butter and cream to chocolate paste is an European contribution which is what makes Belgian and Swiss chocolates so lusciously, mouthwateringly, meltingly delicious. Why is there such an association between chocolate and romance? No one knows for sure but, apparently, Aztec women were forbidden chocolate.
There are reputed health benefits to eating chocolate. It has flavinoids, which are an antioxidant, in it.  These have a beneficial effect on the heart. In fact, 40 grams of  dark chocolate has twice the amount of flavinoids as a glass of wine.  Chocolate's flavinoids may be very effective at reducing cholesterol and blood clotting and reducing the risk of high blood pressure and associated diseases.  It also contains the amino acids phenylalanine, tyrosine, and tryptophan. It has natural stimulants such as theobromine (Greek for "food of the gods") and caffeine which give energy. However, a lot of this research has so far been funded by the chocolate industry so before running out and eating pounds of chocolate a certain caution is advised. The American Dietetic Association says that the toxicological effects of theobromine are not well-researched and it warns against children eating too much chocolate

And, about 25 million Hershey's Ksses come off a conveyor belt every day.

On his fourth voyage to the New World, in 1502, Christopher Columbus
was the first European to taste chocolate.

Americans eat about 10 pounds of chocolate a year per capita.
The Swiss eat 22 pounds per year.

In Hershey, Pennsylvania, the streetlights along "Chocolate Avenue"
are in the shape of Hershey Kisses.

A 1.5 oz. milk chocolate bar has only 220 calories.
A 1.75 oz. serving of potato chips has 230 calories.

Chocolate in a blue wrapper won't sell in Shanghai or Hong Kong
because the Chinese associate blue with death.

Casanova, fond of chocolate's divine properties, considered it an elixer of love.

Queen Victoria was such a devotee that she sent five-hundred-thousand pounds of chocolate to her troops
one Christmas.

Chocolate's scientific name, Theobroma, means food of the gods.

Montezuma, the last Aztec ruler, personally consumed some fifty "pitchers" of chocolate drink each
day and had two thousand "pitchers" prepared for members of his household....( my kind of guy!!)

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"What a waste it is to lose one's mind. Or not to have a mind is being very wasteful. How true that is.".............
Dan Quayle

This is a somewhat more speculative area.

Chocolate contains theobromine, caffeine, phenylethylamine and anandamide, chemicals that are known to affect the brain. Theobromine and caffeine are known to be stimulants. Their effectiveness as a stimulant depends on the amount consumed. It turns out that the amount of caffeine in a chocolate bar is about one-third the amount in a cup of coffee. Consequently, it might be thought of as a mild stimulant.

The phenylethylamine combines with dopamine in the brain to produce a mild antidepressant effect.

The anandamide also affects brain chemistry to produce feelings of calm and well being. The effect is quite small but noticeable.

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"What a waste it is to lose one's mind. Or not to have a mind is being very wasteful. How true that is.".............
Dan Quayle