The Lights of Nefesh, Ruach, Neshama, Haya, and Yechida (the five spiritual degrees) are characterized by a sum of particular details and the power of their unity, despite the fact that they are all in contradiction with one another. It is the only factor that determines the revelation of the upper Light. If we can find unity in the smallest degree, the weakest Light of Nefesh will become revealed as well.
However, why does the Light suddenly become more powerful and is called Ruach? It is because despite the changes and the movement of all interconnected parts, they can still remain balanced and tied. It is as if we keep the boat afloat, while it’s being tossed by waves in a storming sea, and make sure that it keeps stable.
At the first degree of unity, mutual transformations are not yet revealed. Everyone stays in some kind of stationary condition, just as one is, and we seek how to connect with each other. At the second degree, the same unity remains, but every part begins to transform; the cogwheels of the common mechanism as if start spinning relative to each other. And if we stick together despite all these changes and are able to unite, we reveal the Light of Ruach.
These are very limited changes nonetheless: While “staying grounded,” just like a plant, each of us, in our own place, sees the transformation of our individual properties. It is still the same Light of unification but at a higher (“vegetative”) degree. It is followed by a third degree, Neshama (“the animate” degree), where we start moving freely relative to each other, but still reveal unity, “one, unique, and unified,” among ourselves.
This means that the Light we experience in spirituality always depends on the power of our unity, despite any transformation that may be occurring within each of us individually and all of us together. It keeps growing, until we finally reach the end of correction (Gmar Tikkun), while we are experiencing all sorts of changes preventing us from unification in relation to one, single Light, but regardless of this, we are still able to unite.
This is what we call the one, unified spiritual vessel (Echad, Yachid) that receives one Light: Yechida.
From the 1st part of the Daily Kabbalah Lesson 5/5/2011, Shamati No. 56