Chapter 4 contains this statement:

[4] And round about the throne were four and twenty seats: and upon the seats I saw four and twenty elders sitting, clothed in white raiment; and they had on their heads crowns of gold.

24 elders, 24 hoary old men. The 24 horae which are found on old maps.

Chapter 5:

[1] And I saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals.

The 7 celestial bodies of Luna, Mercury, Venus, Sun, Mars, Jupiter and Saturn--in that order. Each planet/god has its own seal. The book is a book of astrology and the one in the throne holding is a master astrologer (Master meaning "ma" or measurer and "ster" or star, a measurer of stars, an astrologer).

Chapter 6:

[1] And I saw when the Lamb opened one of the seals, and I heard, as it were the noise of thunder, one of the four beasts saying, Come and see.
[2] And I saw, and behold a white horse: and he that sat on him had a bow; and a crown was given unto him: and he went forth conquering, and to conquer.
[3] And when he had opened the second seal, I heard the second beast say, Come and see.
[4] And there went out another horse that was red: and power was given to him that sat thereon to take peace from the earth, and that they should kill one another: and there was given unto him a great sword.
[5] And when he had opened the third seal, I heard the third beast say, Come and see. And I beheld, and lo a black horse; and he that sat on him had a pair of balances in his hand.
[6] And I heard a voice in the midst of the four beasts say, A measure of wheat for a penny, and three measures of barley for a penny; and see thou hurt not the oil and the wine.
[7] And when he had opened the fourth seal, I heard the voice of the fourth beast say, Come and see.
[8] And I looked, and behold a pale horse: and his name that sat on him was Death, and Hell followed with him. And power was given unto them over the fourth part of the earth, to kill with sword, and with hunger, and with death, and with the beasts of the earth.

The white horse whose rider wore a crown and and a bow is Sagittarius. The red horse whose rider had the power to make war is Scorpio. The black horse whose rider carried a balance was Libra. And the pale horse whose rider was death is Virgo.

Working our way backwards, the paleness of the horse represents a non-animal sexual energy or the planet kingdom. The ruler of Virgo is Mercury whose sign is that of Venus with horns so is a combination of male and female. The rider is death or a skeleton because ancient peoples thought of plants as having waxy bones (i.e. stems).

The black horse represents the opaqueness of matter, of earth, and so represents the mineral kingdom. The ruler of Libra is Venus. Her sign is a cicle surmounting a cross. The circle represents purity and the cross represents corruption and placed below the circle means "externally pure, internally corrupt." Venus's metal is copper is outwardly gold like the sun but is internally unable to maintain that goldness. Copper was used in coins and so represents money and measurement.

The red horse represents the color of blood and the great sword the rider carries is the venomous stinger of the great scorpion, the dark poisoner. The redness is also Mars who is the ruler of Scorpio. He represents the animal kingdom.

The white horse is purity. The rider's crown is an evolved consciousness above the animal level and the bow represents his ability to focus on something and "conquer" it or completely comprehend it. His consciousness comes from god and so Sagittarius is appropriately ruled by Jupiter ("Ju" is Iu or Yew and "piter" is pater or father--Father Yew).