Kabbalah (Hebrew: קַבָּלָה, literally "reception, tradition" or "correspondance") is an esoteric method, discipline, and school of thought of Judaism. A traditional Kabbalist in Judaism is called a Mequbbāl (מְקוּבָּל). The definition of Kabbalah varies according to the tradition and aims of those following it, from its religious origin as an integral part of Judaism, to its later adaptations in Western esotericism (Christian Kabbalah and Hermetic Qabalah). Jewish Kabbalah is a set of esoteric teachings meant to explain the relationship between God, the unchanging, eternal, and mysterious Ein Sof (אֵין סוֹף, "The Infinite"), and the mortal and finite universe (God's creation). It forms the foundation of mystical religious interpretations within Judaism.
Jewish Kabbalists originally developed their own transmission of sacred texts within the realm of Jewish tradition, and often use classical Jewish scriptures to explain and demonstrate its mystical teachings. These teachings are held by followers in Judaism to define the inner meaning of both the Hebrew Bible and traditional rabbinic literature and their formerly concealed transmitted dimension, as well as to explain the significance of Jewish religious observances. One of the fundamental kabbalistic texts, the Zohar, was first published in the 13th century, and the almost universal form adhered to in modern Judaism is Lurianic Kabbalah.
Sefirot (/sfɪˈroʊt/, /ˈsfɪroʊt/; Hebrew: סְפִירוֹת səphîrôṯ), meaning emanations, are the 10 attributes/emanations in Kabbalah, through which Ein Sof (The Infinite) reveals Itself and continuously creates both the physical realm and the chain of higher metaphysical realms (Seder hishtalshelus). The term is alternatively transliterated into English as sephirot/sephiroth, singular sefirah/sephirah etc.
Alternative configurations of the sefirot are given by different schools in the historical development of Kabbalah, with each articulating different spiritual aspects. The tradition of enumerating 10 is stated in the Sefer Yetzirah, "Ten sefirot of nothingness, ten and not nine, ten and not eleven". As altogether eleven sefirot are listed across the different schemes, two (Keter and Da'at) are seen as unconscious and conscious manifestations of the same principle, conserving the ten categories. The sefirot are described as channels of Divine creative life force or consciousness through which the unknowable Divine essence is revealed to mankind.
This quote contains an interesting view on the interpretation that angels have to appear as us when descending onto our world; as does everything else:
Woe unto the man, says Shimon ben Yochai, who asserts that this Torah intends to relate only commonplace things and secular narratives; for if this were so, then in the present times likewise a Torah might be written with more attractive narratives. In truth, however, the matter is thus: The upper world and the lower are established upon one and the same principle; in the lower world is Israel, in the upper world are the angels. When the angels wish to descend to the lower world, they have to don earthly garments. If this be true of the angels, how much more so of the Torah, for whose sake, indeed, the world and the angels were alike created and exist. The world could simply not have endured to look upon it. Now the narratives of the Torah are its garments. He who thinks that these garments are the Torah itself deserves to perish and have no share in the world to come. Woe unto the fools who look no further when they see an elegant robe! More valuable than the garment is the body which carries it, and more valuable even than that is the soul which animates the body. Fools see only the garment of the Torah, the more intelligent see the body, the wise see the soul, its proper being; and in the Messianic time the 'upper soul' of the Torah will stand revealed.
From the mystical cabalist text, known as the Zohar
The Zohar (Hebrew: זֹהַר, lit. "Splendor" or "Radiance") is the foundational work in the literature of Jewish mystical thought known as Kabbalah. It is a group of books including commentary on the mystical aspects of the Torah (the five books of Moses) and scriptural interpretations as well as material on mysticism, mythical cosmogony, and mystical psychology. The Zohar contains discussions of the nature of God, the origin and structure of the universe, the nature of souls, redemption, the relationship of Ego to Darkness and "true self" to "The Light of God", and the relationship between the "universal energy" and man. Its scriptural exegesis can be considered an esoteric form of the Rabbinic literature known as Midrash, which elaborates on the Torah.
Naphtali Cohen (1649–1718), also known as Naphtali HaKohen Katz, was a Russo-German rabbi and kabalist born in Ostrowo in Ukraine. He belonged to a family of rabbis in Ostrowo, where his father, Isaac Cohen, a great-great-grandson of the Judah Loew ben Bezalel, had fled during the Polish–Cossack–Tatar War. In 1663 Cohen fell into the hands of the Tatars, who kept him in servitude for several years. Escaping, he returned to Ostrowo, and was chosen to succeed his father as rabbi. In 1690 he was called to Posen, where he officiated as chief rabbi until 1704. There he devoted himself to the Kabbalah, and collected a large library of cabalistic literature.