According to Greek mythology, Epimetheus, the first man on earth, was given dominion over the earth and its creatures. In return, He praised Zeus but after a while it became boring to Zeus. He decided to create a mate for Epimetheus. Zeus gathered all the gods together and told them of his idea. From water and earth, Pandora was created. The gods gave her many talents including beauty and music.
When Epimetheus found the gift, he was delighted. He made sure to take special care of Pandora. Soon after, Zeus became bored once again. So he called Hades, god of the underworld, to him and asked him to go to dark places and gather sprites such as hunger, disease, sorrow, etc. Then, Zeus requested that he put them all in a box.
One morning, Epimetheus and Pandora were sitting under an olive tree eating when they noticed a stranger carrying a heavy box. As generous as they were, they offered to help carry the box for the traveler. He agreed. They carried the box as they led the stranger over to the olive tree. After placing the box down gently, Pandora went to fetch the stranger some water. The man accepted the water and asked if he could leave his chest with them while he finished his journey.
Epimetheus told the stranger that he could and that it would be safe with them. The stranger warned them that if they opened the box there could be severe consequences. They both nodded but Pandora couldn't take her eyes off the decorative box. When the traveler left on his journey, he suddenly vanished and Epimetheus knew it was one of the gods.
Soon, Athena's seeds of curiosity were starting to get the best of Pandora. She would spend hours admiring the carvings on the box. She could not read but knew there were words written in gold on top of it. One day when Epimetheus was away, Pandora put her ear to the box to see if she could hear anything. In a faint voice, she heard someone asking for help and wanting her to let them out of the box. After great hesitation, Pandora decided to open the box just a little so she could peek at who was inside. She began to lift the lid realizing how light it was. The creatures inside flew out and surrounded her. She tried to close the box but they tortured her by biting and stinging her. After a while, they went in search of Epimetheus. Pandora couldn't believe what she had done.
She cried as she heard Epimetheus scream from the pain. Suddenly, she heard another voice from the box asking her to release them. After what had just happened, Pandora was very reluctant to do so. But the voice assured her that it wasn't like the others. So, Pandora opened the box once more. A beautiful sprite emerged and began to fly in circles around her healing her wounds. Then it flew to Epimetheus to do the same. Pandora realized that the creature must have been called Hope. After a while, the sprite flew back and rested on Pandora's shoulder. It painlessly drifted into her flesh and found residence in her heart. She then realized that she had been given a gift not to cure pain but to make it easier.
I'm sure there are variations to this story. This is just one of them.
More Info: http://www.pantheon.org/areas/folklore/folktales/articles/pandora.html
*Hoffman, Robert (2005) Pandora's Box. Retrieved May 26, 2005 from the Encyclopedia Mythica web site: http://www.pantheon.org