The Qliphoth, or in Hebrew קליפה (Quoph, Lamed, Yud, Peh, Heh) means “shells”, or “peels”, and is said to be representative of what is left over from “creation”, or however you want to see it, as some see it as an averse side of each Sephiroth, and others see it as a complete tree going further down from Malkuth, into 10 levels beyond Malkuth. Different systems and traditions use different interpretations of this.
Bill Heidrick from the O.T.O wrote an interpretation about this (see page 38) dating back to 1972. Notably, some esoteric orders that don’t relate to the O.T.O, but was founded 1989, use this exact model for their Qliphotic version of the Tree of Life.
They call it the tree of Knowledge. Some occultists (including myself) disagree that the Qliphotic tree itself is the actual “Tree of Knowledge of Good and Evil”.
An Adept once answered my questions regarding working with the Qliphots: “Why do you want to work with dead shells?” (implying as opposed to working with the higher Sephirots)
The real answer to this is from another Adept who said: “It can help you see things in a different way if you are so inclined. But a word of dire warning – this path is not for the faint of heart. Digging into your dark passengers and finding what is at the bottom of the abyss can be a one-way ticket you will not return from”.
I’ve heard interesting recollections from magickal journals from people who have done Astral Travels and pathworking (often referred to as tunneling) in the Qliphoth. The only thing that you have to consider is if you would mentally survive being in a Hellraiser movie. Because that is how the recollections resemble. Or not. 🙂
A speculation on the fundamental symbol of interaction between opposing forces is therefore left to be meditated on as an exercise for the reader.