This illustration for the Book of Revelation is an example of attention he paid to the text he was illustrating and the freedom he used to clarify the significance by his imaginative presentation.
Revelation or the apocalypse was of particular interest to Blake. The Orc cycle or the Circle of Destiny would end when the new age of the spirit begins. The imagery of the Book of Revelation is frightening and hopeful as would be expected when a new age is being born.
Near the climax of Jerusalem we find these words which relate to the image and words from Revelation:
Jerusalem, Plate 98, (E 257)
"And every Man stood Fourfold, each Four Faces had. One to the West One toward the East One to the South One to the North. the Horses Fourfold And the dim Chaos brightend beneath, above, around! Eyed as the Peacock According to the Human Nerves of Sensation, the Four Rivers of the Water of Life"This watercolor represents the vision in the fifth and sixth chapters of the Book of Revelation. Two of the horses of the apocalypse and their riders are represented. Above is the Lamb opening the scroll. The threat of death and destruction is represented in the dark lower half of the picture with Death Riding on a Pale Horse. The hope and promise of the new Jerusalem appears in the Lamb of God surrounded by the light of the sun and the feathers of protection.
Blake's image captures the contrast between the threat and the promise.
Book of Revelations5:10 They sang a new song and these are the words they sang, "You are worthy to take the scroll, and to open its seals; for you were slain, and have redeemed us to God by your blood out of every tribe and tongue and people and nation, and have made us kings and priests to our God; and we shall reign on the earth."
...6:1 - Then I watched while the Lamb broke one of the seven seals, and I heard one of the four living creatures say in a voice of thunder, "Come out!"
6:2 - I looked, and before my eyes was a white horse. Its rider carried a bow, and he was given a crown. He rode out conquering and bent on conquest.
6:3 - Then, when the Lamb broke the second seal, I heard the second living creature, cry, "Come out!"
6:4 - And another horse came forth, red in colour. Its rider was given power to deprive the earth of peace, so that men should kill each other. A huge sword was put into his hand.
6:5a - When the Lamb broke the third seal, I heard the third living creature say, "Come out!"
6:5b-6 - I looked again and there before my eyes was a black horse. Its rider had a pair of scales in his hand, and I heard a voice which seemed to come from the four living creatures, saying, "A quart of wheat for a shilling, and three quarts of barley for a shilling - but no tampering with the oil or the wine!"
6:7 - Then, when he broke the fourth seal I heard the voice of the fourth living creature cry, "Come out!"
6:8 - Again I looked, and there appeared a horse sickly green in colour. The name of its rider was death, and the grave followed close behind him. A quarter of the earth was put into their power, to kill with the sword, by famine, by violence, and through the wild beasts of the earth.