Deprivation ritual

A deprivation ritual was a form of meditation where a Jedi was suspended in a liquid tank with a slowly decreasing air supply, which allowed them to slip into a deep meditative state to become one with the Force as much as possible without dying. After being observed by the Consular Jedi and doctor Rig Nema, Jedi Master Yoda underwent a deprivation ritual during the Clone Wars after he was contacted by the spirit of Qui-Gon Jinn. Undergoing the ritual, he communed with Jinn once again, and was told to go to the planet Dagobah.

Text and facts from the “Deprivation ritual” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.