Force essence

A Force essence was the consciousness and self-awareness of a sentient being. The Darkstaff, a powerful Sith artifact, desired to consume Force essences, and the artifact could also be used to remove Force essences from the bodies of individuals. In about 21 BBY, the Chevin slaver inadvertently caused the staff to rip the Force essences out of several of his slaves and to transfer the essences into a crystal pyramid.