Kether - the eternal, the spiritual perfection

Kether is the first emanation, the level of pure unity, a pure existance with no dependance on anything but itself. It represents the uniqe essence of a subject, regarding to the four elements it is the 'source substance', the very beginning, the first spark of the flame that comes out of universal nothingness.

Kether is the eternal source as well as the spiritual perfection, it is the begin of everything as well as its completion that makes the circle perfect. It corresponds to Yechidah, the all embracing level of soul that stands for the universe itself. It is the ultimate point, total unity, complete unto itself without dimensions or external definition. The journey of manifestation begins and ends with Kether.

The spirit of Kether emanates directly into Chokmah and then into Binah, these three forming the Supernal Triangle.

In the Minor Arcana, Kether is represented by the Aces, which are the roots and entity of the elements they stand for. They imply the unity of the number 1 and are the pureness of their elements, but also they are just the seeds. (corax.com)