And out of the ground the LORD God made to grow every tree that is pleasant to the sight and good for food, the tree of life also in the midst of the garden, and the tree of the knowledge of good and evil.
 And the LORD God commanded the man, saying, "You may freely eat of every tree of the garden;
 but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall die."
The drama which took place in the Garden of Eden revolved around the tree which bore the fruit which if eaten would provide knowledge of Good & Evil. Without that knowledge nothing was of greater or lesser value. Thinking as Blake did that man could return to Eden at any time, this knowledge of Good & Evil became a pivotal point for him.
As Blake worked it out, man, as a consequence of dualistic thinking, named an opposed characteristics to each entity he identified. Then he compounded his error by declaring one of the pair good and the other evil. Himself and what he preferred, he identified with the good, and the other object, person, idea or word he identified with evil. From this description it is apparent that good and evil are arbitrary.
In the two previous posts on the Large Color Prints, the Fall of man was seen as the consequence of division: man dividing from God, then man dividing from woman. In the Good & Evil Angels Struggling for Possession of a Child we see that the process of division has come to permeate everything. And that the divisions lead to contentions between two sides seeking dominance. To Blake the dualistic thinking which leads to the labels of good and evil is the root of the whole process of accusation, condemnation and vengeance. Brotherhood cannot come until the other is not seen as evil.
The Good and Evil Angels Struggling for Possession of a Child
In the Editors' Notes for this picture in the Blake Archive we read:
"The color print may also indicate the fall into the errors of the good/evil, body/soul, energy/reason dualities. The child may thus represent humanity caught between these contending oppositions."
A Vision of The Last Judgment, (E 554) For the Year 1810 Additions to Blakes Catalogue of Pictures &c "The Last Judgment when all those are Cast away who trouble Religion with Questions concerning Good & Evil or Eating of the Tree of those Knowledges or Reasonings which hinder the Vision of God turning all into a Consuming fire
Imaginative Art & Science & all Intellectual Gifts all the Gifts of the Holy Ghost are [despisd] lookd upon as of no use & only Contention remains to Man then the Last Judgment begins & its Vision is seen by the [Imaginative Eye] of Every one according to the situation he holds" A Vision of The Last Judgment, (E 562) "Here they are no longer talking of what is Good & Evil or of what is Right or Wrong & puzzling themselves in Satans [Maze] Labyrinth But are Conversing with Eternal Realities as they Exist in the Human Imagination We are in a World of Generation & death & this world we must cast off" A Vision of The Last Judgment, (E 563) "By this it will be seen that I do not consider either the Just or the Wicked to be in a Supreme State but to be every one of them States of the Sleep which the Soul may fall into in its Deadly Dreams of Good & Evil when it leaves Paradise [with] the Serpent" A Vision of The Last Judgment, (E 564) "Nothing is displeasing to God but Unbelief & Eating of the Tree of Knowledge of Good & Evil Men are admitted into Heaven not because they have governd their Passions or have No Passions but because they have Cultivated their Understandings. The Treasures of Heaven are not Negations of Passion but Realities of Intellect from which All the Passions Emanate in their Eternal Glory The Fool shall not enter into Heaven let him be ever so Holy. Holiness is not The Price of Enterance into Heaven Those who are cast out Are All Those who having no Passions of their own because No Intellect. Have spent their lives in Curbing & Governing other Peoples by the Various arts of Poverty & Cruelty of all kinds"