Without Klipa we cannot identify the Kedusha (sanctity) because seeing the advantage of the Light is through its contrast with darkness. If we want to draw a line between any two properties, we must see both, one characteristic and the other that is differing from the first. We need boundaries, limitations, definitions, differences, and only the system of impure forces (Klipot) can provide this to me, and more qualitatively each time.
It is an extraordinary ingenious system that works in the form inverse to that of sanctity, but in a way that brings a person to sanctity. And therefore it requires a double trick. It is like an adult in playing with a small child tries to show him all his shortcomings, but in an enticing way so that the child will not run away. He shows all the means that will help the child along the way in order to teach the child how to use them himself, to teach him how to attain these powers himself.
On every level, the Klipa brings a person to a final stage of development, (Behina Dalet), where he begins to have control over himself. And then he is ready to build sanctity above it. It is so cleverly arranged that it’s as if it is fooling itself, producing double opposites. Therefore Klipa is considered insidious and cunning, but all of its deceit is directed towards the goal of creation. The system is constructed this way from above.
The question is: “How can we identify the Klipa if it is so tricky?” We can identify it according to the intention because it shows me that my intention is still not to bestow, Lo Lishma.
The Klipa is anything other than the opportunity to contact and reach the Creator, as it is said: “Another god is sterile and bears no fruit.” Through the Klipa, I cannot connect with the Creator. And only if I am to give up everything for the sake of the Creator, even if only for a moment, and to bestow to Him in one direction without regard for anything in exchange, then the gates are opened and I pass from Klipa to Kedusha. This is the only thing that is lacking in the system of impure forces and is found in the system of sanctity: contact with the Creator with unidirectional bestowal, only from me to Him.
From the 2nd part of the Daily Kabbalah Lesson 8/13/13, The Zohar