Eve is the figure who transitions Eden to generation. Kathleen Raine, on page 41 of Blake and Antiquity, tells us that the birds with Eve are the 'lureing birds of love.'
Book of Urizen, Plate 18, (E 78) "9. All Eternity shudderd at sight Of the first female now separate Pale as a cloud of snow Waving before the face of Los 10. Wonder, awe, fear, astonishment, Petrify the eternal myriads; At the first female form now separate Plate 19 They call'd her Pity, and fled" Jerusalem, Plate 86, (E 245) "And Enitharmon like a faint rainbow waved before him Filling with Fibres from his loins which reddend with desire Into a Globe of blood beneath his bosom trembling in darkness Of Albions clouds. he fed it, with his tears & bitter groans Hiding his Spectre in invisibility from the timorous Shade Till it became a separated cloud of beauty grace & love Among the darkness of his Furnaces dividing asunder till She separated stood before him a lovely Female weeping Even Enitharmon separated outside, & his Loins closed And heal'd after the separation: his pains he soon forgot: Lured by her beauty outside of himself in shadowy grief. Two Wills they had; Two Intellects: & not as in times of old. Silent they wanderd hand in hand like two Infants wandring From Enion in the desarts, terrified at each others beauty Envying each other yet desiring, in all devouring Love,"The primary characteristic of the fall of man to Blake was not disobedience or sin but the loss of the awareness of Eternity with its attendant inability to perceive that one is known by God and knows God intuitively. Paul's book of Romans says something of the same when he speaks of man losing the power of seeing the 'invisible nature' of the created world, and worshiping the images rather than the creator.
 For what can be known about God is plain to them, because God has shown it to them.
 Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made. So they are without excuse;
 for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking and their senseless minds were darkened.
 Claiming to be wise, they became fools,
 and exchanged the glory of the immortal God for images resembling mortal man or birds or animals or reptiles.
 Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves,
 because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed for ever! Amen.