Pandora's Pithos

"A Greek vase appeared on the table. It was about three feet high and a foot wide, glazed with black-and-white geometrical designs. The ceramic lid was fastened with a leather harness."

- Percy describing the pithos

Pandora's Pithos (in Ancient Greek: πίθος, also known as Pandora's Jar or Pandora's Box) was once the "home" to all the evils of the world. When curious Pandora opened it, all the evils that hunt mankind escaped and made life worse for humans. It is currently owned by the goddess Hestia and only one more spirit remains inside; the spirit of Hope, Elpis.

History
Pandora's Pithos was given to Pandora, the first woman, who in turn was given to Epimetheus by the gods. It was really a punishment for Prometheus for taking fire from the gods. They knew he would get angry if he saw his creations being tormented. So they gave Pandora the jar and told her not to open it no matter what. Percy remarked in The Last Olympian, that Pandora must have been "totally ADHD" like him and the curiosity was probably killing her. When Pandora did open the jar and everything evil that mankind is tormented by, such as lies, murder, treason, and all bad spirits and ideas escaped from that jar. The first Empousa was also released. Only Elpis (Hope) remained.

The Last Olympian
When Prometheus meets with Percy, he gives him the jar. At the time, only Hope was left in the jar. He tells Percy that when he is ready to surrender to Kronos, he should open it, giving up hope. Although Percy puts it in        the hotel's safe, it follows him around, and appears whenever he is at his weakest, tempting him to open it. Percy later gives it to Hestia stating "hope survives best at the hearth".

Trivia

 * Most mortals call it a jar or box, rather than a Pithos, an Ancient Greek storage jar.
 * Prometheus is clueless as how the word box/jar came about, but admits that "Pandora's pithos" just doesn't have the same ring to it.