The following passage is related to the Biblical fall reported in Genesis. But Blake has different ideas about what was going on. Los and Enitharmon are taking the roles of Adam and Eve in eating the 'ruddy fruit.'
Four Zoas, Night VII, Page 97, (E 368)
"But Los stood on the Limit of Translucence weeping & trembling
Filled with doubts in self accusation beheld the fruit
Of Urizens Mysterious tree For Enitharmon thus spake
When In the Deeps beneath I gatherd of this ruddy fruit
It was by that I knew that I had Sinnd & then I knew
That without a ransom I could not be savd from Eternal death
That Life lives upon Death & by devouring appetite
All things subsist on one another thenceforth in Despair
I spend my glowing time but thou art strong & mighty
To bear this Self conviction take then Eat thou also of
The fruit & give me proof of life Eternal or I die
Then Los plucked the fruit & Eat & sat down in Despair
And must have given himself to death Eternal But
Urthonas spectre in part mingling with him comforted him
Being a medium between him & Enitharmon But This Union
Was not to be Effected without Cares & Sorrows & Troubles
Of six thousand Years of self denial and of bitter Contrition t
Urthonas Spectre terrified beheld the Spectres of the Dead
Each Male formd without a counterpart without a concentering
The Spectre of Urthona wept before Los Saying I am the cause
That this dire state commences I began the dreadful state
Of Separation & on my dark head the curse & punishment
Must fall unless a way be found to Ransom & Redeem
But I have thee my [Counterpart Vegetating] miraculous
These Spectres have no [Counter(parts)] therefore they
Without the food of life Let us Create them Coun[terparts]
For without a Created body the Spectre is Eternal Death
Los trembling answerd Now I feel the weight of stern repentance
Tremble not so my Enitharmon at the awful gates
Of thy poor broken Heart I see thee like a shadow withering
As on the outside of Existence but look! behold! take comfort!
Turn inwardly thine Eyes & there behold the Lamb of God
Clothed in Luvahs robes of blood descending to redeem
O Spectre of Urthona take comfort O Enitharmon
Couldst thou but cease from terror & trembling & affright
When I appear before thee in forgiveness of ancient injuries
Why shouldst thou remember & be afraid. I surely have died in
Often enough to convince thy jealousy & fear & terror
Come hither be patient let us converse together because
I also tremble at myself & at all my former life
Enitharmon answerd I behold the Lamb of God descending
To Meet these Spectres of the Dead I therefore fear that he
Will give us to Eternal Death fit punishment for such
Hideous offenders Uttermost extinction in eternal pain
An ever dying life of stifling & obstruction shut out
Of existence to be a sign & terror to all who behold
Lest any should in futurity do as we have done in heaven
Such is our state nor will the Son of God redeem us but destroy
PAGE 98 
So Enitharmon spoke trembling & in torrents of tears"
Enitharmon and Los have played the parts of Eve and Adam and have partaken of the fruit of the tree of knowledge of good an evil. They have become aware that they have sinned, have repented and feel that they are deserving of Eternal Death unless they are ransomed. The Spectres of the Dead 'wandering fragments of spirit ... which have not yet been incarnated' (Damon), in order to escape Eternal Death need created bodies.
Seeing a disheartening situation the Spectre of Urthona recognizes his share of responsibility and supplies the will missing from Los as a division of Urthona.
Los feels the weight of stern repentance. Through his awareness, Los is able to pity Enitharmon who is in a state of fear and trembling. Los advises Enitharmon to look inward and behold the 'Lamb of God Clothed in Luvahs robes of blood descending to redeem'. Los tries to convince Enitharmon to give up her fears because she has been forgiven. She is convinced and sees the Lamb of God herself but she still fears that they will be destroyed and not redeemed.
The story will continue in my next post but feel free to read ahead!