This picture of a scene in Revelations is said to be public domain. Putting Blake's pictures directly into a post should certainly make it easier for the reader to grasp what is being said by it.
1And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars:
2And she being with child cried, travailing in birth, and pained to be delivered.
3And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads.
4And his tail drew the third part of the stars of heaven, and did cast them to the earth: and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born.
5And she brought forth a man child, who was to rule all nations with a rod of iron: and her child was caught up unto God, and to his throne.
6And the woman fled into the wilderness, where she hath a place prepared of God, that they should feed her there a thousand two hundred and threescore days.
7And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8And prevailed not; neither was their place found any more in heaven.
(Blake would not have agreed with John's 'rod of iron', thinking as he did that Jesus was forgiveness. John was quoting a psalm when he used that figure.)
From Blake: PLATE 12 or 13 of Milton
"For her light is terrible to me. I fade before her immortal beauty.
O wherefore doth a Dragon-form forth issue from
my limbs To sieze her new born son?" (E105)
Here Leutha forecasts what is described in Revelation
"Abraham, Moses, Solomon, Paul, Constantine, Charlemaine
Luther, these seven are the Male-Females, the Dragon Forms
Religion hid inWar, a Dragon red & hidden Harlot"
(This from Plate 37 of Milton) (E138)
"No sooner she had spoke but Rahab Babylon appeard
Eastward upon the Paved work across Europe & Asia
Glorious as the midday Sun in Satans bosom glowing:
A Female hidden in a Male, Religion hidden in War
Namd Moral Virtue; cruel two-fold Monster shining bright
A Dragon red & hidden Harlot which John in Patmos saw"
This adequately reflects the top half of the picture. When you may engage in the universal sea of Erdman's Blake text you will find a more complete statement of the above at the end of Plate 77 of Jerusalem.