We feel like we receive a “shadow,” the darkness, but this is because a greater Light comes while I am not yet prepared to receive or perceive it properly. Therefore, I sense darkness, the contrast between us. In other words, the feeling of descent is the revelation of new desires (Kelim) where for now I perceive how opposite they are to the Light that influences me.
If I am ready, then a greater Light reveals a greater desire within me. However, as long as the Light and the desire have opposite intentions (the Light has the intention to bestow, while the desire has the intention to receive), I perceive this distance between them as a descent.
Yet, this state needs to be appreciated because, essentially, this is already the opposite side of a higher degree. All sensations of darkness, descents, and rejection come from a new, stronger Light that reveals greater desires (Kelim) in us.
I exist in an infinite desire (Kli); my soul is infinite. After all, there are no creatures besides me; all the others are parts of my soul. The Light gradually increases and reveals greater layers of the desire within me.
The more the Light shines, the greater the desire that becomes revealed. When a stronger Light comes to me, it reveals an even stronger corresponding desire. But every time a new desire is revealed, I perceive it as greater separation between myself and “spirituality,” the force of life, because the properties of the desire are opposite to those of the Light, and so I feel bad. One needs to prepare himself for this state ahead of time so that when it comes, he would understand that it awakens him towards correction.
If I did not feel evil, the fall into separation between myself and the Light, I would not be able to begin correction. The revelation of evil is intended to push me ahead. For this reason, the feeling of a “shadow” of the impure worlds (Tzel de Tuma) is necessary in order to attain the “holy shadow” (Tzel de Kedusha). We should value these shadows.
From the Hoshana Rabbah Night Lesson 9/29/10, Shamati #243