Yetzirah

Yetzirah - the World of Formation represented by the 22 letters of the Hebrew alphabet as described in the Sefer Yetzirah. In the innermost segment, the 3 mothers, followed by the 7 doubles and the 12 singles.

Yetzirah (Hebrew: יצירה "formation, transformation, creation") resp. Olam Yetzirah Hebrew: עוֹלָם יְצִירָה, the "World of Formation", is, according to the teachings of the Jewish Kabbalah, the third of the four worlds and corresponds in anthroposophical terminology largely to the astral world, whose lowest three areas, however, overlap with the 3 uppermost areas of the etheric world (→ 7 regions of the astral world). On the Tree of Life of the Kabbalah, Yetzirah comprises the three sefirot Netzach (overcoming), Hod (compassion) and Yesod (foundation). The air element and the third letter of the tetragrammaton JHVH (Hebrew: יהוה Yahweh), i.e. the Waw (ו), are assigned to her.

In the Sefer Yetzirah, the oldest surviving work of Kabbalah, the forces that work in world of Yetzirah are assigned to the 22 letters of the Hebrew alphabet, which are divided into three groups:

Group	Letters	Assignment
3 Mothers	ש  מ  א Aleph, Mem, Schin	Air - Water - Fire
7 Singles	ת  ר  פ  כ  ד  ג   ב Beth, Gimel, Daleth, Kaph, Peh, Resch, Thaw	7 planets (from Saturn to Moon), 7 days of the week, 7 gates of the senses on the human head: two eyes, two ears, two nostrils, mouth.
12 Doubles	ק  צ  ע  ס  נ  ל  י  ט  ח  ז   ו  ה Heh, Waw, Sajin, Cheth, Tet, Jod, Lamed, Nun, Samech, Ajin, Zade, Qoph	12 constellations (from Aries to Pisces), 12 months, 12 organs of the human body.