One is the breath of the Living God
Blessed and benedicted
Is the name of the Life of the Worlds,
The voice of breath and speech,
And it is the Holy Breath.
— Sepher Yetzirah

Kether is the divine Crown, all that is and the breath of that which is Not. From it we come; to it we shall return.

Kether is our most direct possible apprehension of the Divine Glory, that light which surpasses the glory of the Sun and beside which the light of mortals is but darkness, and concerning which it is not fitting that we should speak more fully. Its sphere of operation is called Rashith ha-Gilgalim, the beginning of whirling, the Primum Mobile or First Mover, which bestows the gift of life in all things and fills the whole Universe.

...But fitting or not fitting, there is more to say about the Primum Mobile. Meditate upon this, O seeker:

Cut Time up into its smallest possible instants. Chop it as finely as you like. When you're done, when you can't divide it any more finely, there exists an instant before an action begins, and an instant in which it has begun. In between those two instants — between which nothing can be! — Something happens, the action begins. Whatever happens, happens between those two instants, in a place we can't see, can't touch, can't measure; all we can do is observe its effect, which is the action. What is that Something? We can't know. All we can say about it is, And there was Light.