Letters are qualities which our desire accepts under the influence of the Light that Reforms. The Creator has created matter, meaning our desire to receive pleasure. Under the influence of the Light, this desire takes different forms or qualities similar to the Light.
On its own, matter is the desire to receive pleasure, the desire for fulfillment. But with the help of the Light, it acquires higher forms that are opposite to its nature, the qualities of love and bestowal. We refer to these qualities as forms because they emanate from the desire and project to the outside. The desire acquires an external form that can be recognized. If it was simply matter, I wouldn’t be able to perceive it. I recognize it because it has a certain form like a circle, square, or rectangle. I wouldn’t recognize it without a form.
The Light influences the desire to receive pleasure by creating different "protuberances and cavities" in it, thereby enabling it to distinguish itself through the qualities of bestowal which initially do not exist in the desire. These qualities are built over the desire, as if they were beginning to emerge from it. This is why we refer to these qualities as forms. What does a "form" mean? Matter which in a way has become similar to the Light is called the form of matter.
In total there are 27 of these forms: 22 letters from "Aleph" to "Tav" and 5 ending forms, MaNTZePaCH. Why is this so? This is because there are 22 forms of bestowal that emanate from ZAT de Bina (parts of Bina that influence us): 9 from Bina, 9 from Zeir Anpin and 4 from Malchut, as well as 5 end forms (forms of limitations).
This is why we have 27 forms that our matter accepts under the influence of the Light. For this reason we can use these 27 forms in order to explain what the Creator is doing to us, what He wants from us, and how we can become like Him in the 27 forms which we acquire under the Light’s influence on our world. But so far our matter completely lacks form; it is nothing but a mount of desires.
From the Evening Zohar Lesson 5/13/10
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