The Fifty Gates of Wisdom
The "Tree of Life"
The relationship between the ten Sefirot, (and the "Sefirah" of Da'at), is ruled by three Divine principles: Mercy, Justice and Will (or Grace). As such, the Sefirot are presented in three "columns" or "pillars". This arrangement is known as the "Tree of Life".
Notice that in the Tree of Life diagram, "east" is to the top, "south" to the right, "west" to the bottom and "north" to the left.
Those Sefirot ruled by Mercy are on the right and are governed by the Sefirah of Chokmah (Wisdom).
This is said to be the expansive or active side. Think of God's mercy as "enduring forever".
The Sefirot on the left side are ruled by Justice are governed by the Sefirah of Binah (Understanding).
This is considered to be the constrictive or passive side. Think of justice being "firm".
Lastly, the middle pillar, ruled by the Sefirah of Keter (Crown), and associated with the Will (or Grace) of God,
is one of equilibrium or perfect harmony.
The center pillar runs from Keter to Malkut, which represent the dimensional range of good to evil.
This middle pillar is associated with the "Tree of Knowledge",
having to do with the mystery of the "Tree of Knowledge of Good and Evil" mentioned in Bereshyit 2:9.
An example of these three pillars is related in the Zohar, which speaks of the Patriarchs having relationships to the various attributes of God, with Ya'kov as the central pillar bringing harmony to the judgmental side of Yitzhak and the merciful side of Avraham.
The outer columns are referred to in masculine and feminine terms. They are called Father and Mother as stated in the Encyclopedia Judaica: "The Sefirot Hokhmah and Binah now become the parzufim of Abba and Imma (Father and Mother)" - Kabbalah p. 599). The concept of HaShem being expressed as a Father (Yeshayahu 63:16; 64:8; Yirmeyahu 31:9 & Mal'akhi 1:6) and a Mother (Yeshayahu 66:13) is found in the Tanakh, in which we are told that the image of God in which man was created was "male and female" (Bereshyit 1:26-27). The Hebrew phrase "Ruach HaKodesh" (Spirit of Holiness, Holy Spirit) is grammatically feminine and is therefore interchangeably termed "Mother" and identified with the feminine aspect of God, or "Shekinah".
"In the beginning, G-d created
The Heaven and the Earth
And the light and the dark
G-d created man
In His own image
In the image of G-d He created us
Black and white,
For life and love..."
(Ofra Haza - "Genesis")
The "middle pillar" of the Tree of Life is closely associated with Ya'kov, the Messiah, Malkitzedek, Henok, and the mysterious Metatron. This middle pillar (the pillar of equilibrium) strikes the "balance" between the masculine and feminine sides:
Zohar, p. 227 - "The Middle Pillar [of the Godhead] is Metatron, Who has accomplished peace above, according to the glorious state there.".
As the Sefirotic "Tree of Life" is in the image of God, and the rest of Creation came through this, we can then expect to see some type of Sefirot pattern within Creation.
The Universe is based on order; its basic pattern is summed up in the Laws embodied in the Sefirotic Tree.