I am going to share with you some interpretation that the ESV Study Bible by Crossway Books shares in the footnotes.  You wonder what the color of the horse has anything to do with the seals?  First off I would like to explain that there are different interpretations of this book.  Without going into detail of any of them,  I want to say, that I'm not sure where I even stand in it all.  To be honest I think, one day we will see how these "events" play out, and as long as I'm on the right team, I trust that God has everything under His control and whatever happens will be just.   So, the horses. The first horse that is mentioned is white.  Some scholars think this color is to signify Christ, some think the Antichrist and yet others, political and military leaders.  If it is a picture of political and military leaders, they have been destabilized in their quest to expand their realms leading to war. The second horse is red, signifying blood.  The rider on this horse has been given permission to take peace from the earth through bloodshed. The third horse is black signifying famine.  The rider carries scales for measuring grain and their prices.  Prices of food will increase greatly and there will be great famine.  The fourth and final horse is pale in color.  The greek describes this color as "pale green" being either yellowish-green or grayish-green.  Either way, both are similar to that of a corpse.  The authority has been given to this rider to kill a quarter of the earth most likely with an epidemic disease. 

Read verses 9-17 again.  I think the text explains itself perfectly:

When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne.  They cried out with a loud voice, "O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?"  Then they were each given a white robe and told to rest a little longer, until the number of their fellow servants and their brothers should be complete, who were to be killed as they themselves had been.

When he opened the sixth seal, I looked, and behold, there was a great earthquake, and the sun became black as sackcloth, the full moon became like blood, and the starts of the sky fell to the earth as the fig tree sheds its winter fruit when shaken by a gale.  The sky vanished like a scroll that is being rolled up, and every mountain and island was removed from its place.  Then the kings of the earth and the great ones and the generals and the rich and the powerful, and everone, slave and free, hid themselves in the cabes and among the rocks of the mountains and rocks, "Fall on us and hide us from the face of him who is seated on the throne, and from the wrath of the Lamb, for the great day of their wrath has come, and who can stand?"

        Kind of crazy, eh?  I don't understand all of this, as much of you don't- but whether this is completely literal or whether it is metamorphical, God wants us to know, through this revelation of John's, that His wrath will be poured out on those who don't love and follow Him.  Reading this again, I am so glad that God calls me His own!  Regardless of which interpretation you agree with (Historicism, Futurism, Preterism or Idealism) or whether you believe in the Millenial views, Postmillenial views or the Amillennialism views- God is just.  So if you have obeyed Him and His word, then you will have favor in his eyes.   If you haven't heard or familiarized yourself with the 4 "isms" and 3 "millenials" you can research them on your own.  They are outlined in the ESV Study Bible.  Although it's fascinating to know all the different opinions and views, we won't know for sure which is true until the end of the age.  So for me, I would like to be in the know, but not stress over which is true and which is false.  I would however, make sure you are in right standing with the Almighty- who; the four creatures, the four horses, the seven seals, the scroll, the sky and the earthquake all will listen to whenever the big day comes. 

On Revelation Chapter 6

• Leanne