Da'at or Daath is not considered a seperah. Some have called it the shadowy seperah or the false seperah. Daath is important to the tree though. It is rather a state of Gnosis or knowing. Da'at means knowledge in Hebrew. Chokmah is the masculine father and Binah is the feminine mother(see Chokmah and Binah). Daath is like the son, the end result, so the other realms can appear. Daath is the bridge to the real world and it is located in the abyss.
What lies after the Supernal triad between the next triad(Briah) is the abyss. The Supernal triad is the real and pure triad. The next triad of Briah or etheric triad is the mere reflection of the Supernal and then the third triad (astral triad) is a dense reflection of the etheric:eventually the physical state of matter is manifested. The abyss works kind of like a mirror. Think of it like this, in your bathroom the mirror is the abyss and you are looking through the mirror and you see the illusionary reflection of the real you.
Daath is shadowy and hidden. According to the Hebrew kabbalists, people who remain selfish cannot see it and for them Daath seems “hidden”. So then, egotism is like a blockage to the source and higher consciousness. Daath’s virtue is detachment. Dion Fortune writes “Perfection of Justice and the application of the Virtues untainted by considerations of the personality.” The virtue of Detachment indicates what is required to unify our mundane selves with our spiritual selves. Daath operates in two levels: the lower is the Daath(knowledge) you’ve attained with the lower seperoit which are the emotional and intellectual ones(Chesed to Yesod) used in the right action. The higher level is the Daath of Kether the Gnosis\enlightenment you’ve attained from Kether.
