Although we hear of the birth of these characters,
some from others, they are actually manifestations
of the four functions (later celebrated by Carl Jung).
Blake called The Four Zoas Vala in the beginning.
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; [E358])
So we can see that in Blake's myth Vala occupied the
same symbolic role that Eve did in the Garden.