Essence, also known as vliya, which translates to "blue fire", was the life force of all living beings. During the final years of the Age of Division, the Skeksis began draining Gelfling of their essence in order to attain immortality, an act which resulted in the spread of the Darkening and the collapse of the Alliance of the Crystal. When the Gelfling were largely exterminated during the Garthim War, the Podlings became the new targets for essence extraction.
When extracted, Gelfling essence manifested itself in a glowing whitish-pink liquid. When a Gelfling died, its essence would return to Thra, thus restoring the planet's balance and preventing the spread of the Darkening. Full draining resulted in the victim evaporating in an explosion of light, while partial draining caused subjects to visibly age and lose all higher mental functions, thus rendering them susceptible to suggestion.
Gelfling essence had the effect of temporarily rejuvenating the Skeksis when consumed, restoring their strength and healing their infirmities. It also had an intoxicating effect when imbibed in large quantities, causing the Skeksis to audibly slur their speech, lose inhibition and act jovially. Podling essence was notably poorer in quality, lacking the glow characteristic of Gelfling essence, and restoring vigor for only a few seconds.
During the mid to late Age of Division, skekGra and urGoh, in an attempt to weaponize the Shard of the Division, forged the Dual Glaive, a weapon with the ability to drain its victims of essence. Ordon used it to attain victory during the First Battle of Stone-in-the-Wood, but hid it away after learning of its life-draining properties, fearing its misuse.
30 trine later, skekTek, while attempting to force the Crystal to relinquish its life-giving properties, accidentally reversed its magnetostatic field, causing it to partially drain him of his essence. Seeing an opportunity to cheat death, skekSil suggested harvesting the essence of Gelfling, as they were the beings closest to Thra, and thus richest in the substance.
While jubilant over the prospect of immortality, the Skeksis were divided over how best to proceed: both skekSil and skekTek advocated a limited harvest, the former reasoning that it was necessary to ensure a steady supply and to preserve the Alliance of the Crystal, while the latter was concerned that overconsumption would have resulted in the destruction of Thra. The two were overruled by a faction consisting of skekSo, skekVar, skekAyuk and skekLach, who rejected their calls for moderation.
After having coerced skekTek into revealing the number of Gelfling needed to keep the Skeksis alive indefinitely, skekSo demanded an annual tribute of seven Gelfling from each Gelfling Clan, concocting a fabricated war against the Arathim as a pretext for their enrollment and subsequent disappearance. The Skeksis were, however, unable to maintain the pretense, as their actions were causing the Darkening to spread faster, and news of their betrayal had been spread by Rian and Aughra. The Skeksis then accelerated their essence draining, starting with the Castle Guards and the Stonewood rebels.
After the Garthim War, with the Gelfling largely exterminated, Podlings became the new targets of essence extraction. Due to the poor quality of Podling essence and the need for only partial draining in order to maintain a staff of slaves, skekSo decreed that essence consumption was the sole prerogative of the Emperor, a privilege later inherited by his successor skekUng.
- Age of Resistance – "What Was Sundered and Undone". Netflix. August 30, 2019
- Age of Resistance – "End. Begin. All the Same.". Netflix. August 30, 2019
- Henson, J. & Oz, F. (dir.); Henson, J., Kurtz, G. & Lazer, D. (prod.); Henson, J. & Odell, D. (writ.) (December 17, 1982). The Dark Crystal (Motion picture). New York City, NY: Jim Henson Productions.
- Age of Resistance – "Prophets Don't Know Everything". Netflix. August 30, 2019
- Age of Resistance – "By Gelfling Hand...". Netflix. August 30, 2019
- – Andelfinger, Nicole., Age of Resistance – The Quest for the Dual Glaive, #4, Archaia, USA, December 2019
- Age of Resistance – "The First Thing I Remember Is Fire". Netflix. August 30, 2019