Evil spirits came from giants that died back in the times before the Great Flood. The giants were evil. They were half angel (celestial - from heaven - spirits that never die) and half human (terrestrial - from earth - they die and return to dust). When the giants died, their human bodies died, but their spirits lived. Those spirits are hungry and thirsty and they look for a body to live in again, so they can try to feel and eat and drink again. They are invisible to most people and they cause sadness. They are also called the spirits of the wicked and terrestrial spirits. They can't ever go back to heaven. They will never know peace.