mysterium-esoterica:

The Kabbalistic Tree of Life has a dark side, the Tree of Qliphoth, which is also known as the Tree of Death and which corresponds to the Tree of Knowledge in the Bible. The Qliphoth are metaphorical “shells” surrounding holiness. They are spiritual obstacles receiving their existence from God only in an external, rather than internal manner. Divinity in Judaism connotes revelation of God’s true unity, while the shells conceal holiness, as a peel conceals the fruit within.