Vala

In the beginning Blake called The Four Zoas Vala. The emanation of Luvah, she has a checkered career. In Eternity she is Jerusalem; fallen she became Vala, somewhat comparable to Eve in the garden. She carries all creation, all love, but in Ulro love is totally bad (not so in regeneration and in Eternity).

Vala was the contrary (opposite) of Jerusalem (the bride of Christ). She represents all the negativity of the feminine character. She also goes by the names of Rahab and Tirzah.

"Among the Flowers of Beulah walkd the Eternal Man & Saw
Vala the lilly of the desart. Melting in high noon
Upon her bosom in sweet bliss he fainted. Wonder siezd
All heaven, they saw him dark. They built a golden wall
Round Beulah. There he reveld in delight among the Flowers.
Vala was pregnant & brought forth Urizen, Prince of Light,
First born of Generation. Then behold: a wonder to the Eyes
Of the now fallen Man a double form Vala appeard. A Male
And female; shuddring pale the Fallen Man recoild
From the Enormity & calld them Luvah & Vala. Turning down
The vales to find his way back into Heaven, but found none
For his frail eyes were faded & his ears heavy & dull."
(Four Zoas, 7a:83:8-18, E 358)

Hear Vala in the beginning of the poem:

"Hear! I will sing a Song of Death! it is a Song of Vala!
The Fallen Man takes his repose: Urizen sleeps in the porch
Luvah and Vala woke & flew up from the Human Heart
Into the Brain; from thence upon the pillow Vala slumber'd.
And Luvah seiz'd the Horses of Light, & rose into the Chariot of Day
Sweet laughter siezd me in my sleep! silent & close I laughd
For in the visions of Vala I walkd with the mighty Fallen One
I heard his voice among the branches, & among sweet flowers."
(Four Zoas 1:10-16, E 305)

So we can see that in Blake's myth Vala occupied the same symbolic role that Eve did in the Garden.

In The Four Zoas Blake used two kinds of daughters , who collectively represented Jerusalem and Vala:
1. Daughters of Beulah (Inspiration) are devoted to the well-being of man. They guarded the body of Albion in his mortal sleep on the Rock of Ages.

2. Daughters of Albion (Memory), obeying Reason weave the natural world of spiritual depravity.

In the poem Jerusalem we read: "The fallen Albion meets Vala and hears her say "Know me now Albion: look upon me. I alone am Beauty The Imaginative Human Form is but a breathing of Vala. I breathe him forth into the Heaven from my secret Cave, Born of the Woman to obey the Woman O Albion the mighty For the Divine appearance is Brotherhood, but I am love." (Jerusalem 29.49-52; E176)

And this from wiki : "Albion and Vala are deeply connected in Blake's myth. Originally, Albion was also with Jerusalem, but he abandons her after she claims that both Vala and Albion are too obsessed with the idea of sin. Jerusalem's fall provokes Vala to claim that she is the triumphant beauty and embraces materialism along with statements that women are dominant. Los rejects these claims and defends mankind. Although she has entered into a fallen state, from her line Jesus would be born. In the fallen state, she promotes revenge, jealousy, and justice during war. When she is redeemed after the Final Judgment, she is joined [as Jerusalem] with Albion as his bride. This allows for a union between mankind and the divine."

More on Vala may be found here and here.