6:1 Now I watched when the Lamb opened one of the seven seals, and I heard one of the four living creatures say with a voice like thunder, “Come!” 2 And I looked, and behold, a white horse! And its rider had a bow, and a crown was given to him, and he came out conquering, and to conquer.
3 When he opened the second seal, I heard the second living creature say, “Come!” 4 And out came another horse, bright red. Its rider was permitted to take peace from the earth, so that people should slay one another, and he was given a great sword.
5 When he opened the third seal, I heard the third living creature say, “Come!” And I looked, and behold, a black horse! And its rider had a pair of scales in his hand. 6 And I heard what seemed to be a voice in the midst of the four living creatures, saying, “A quart  of wheat for a denarius,  and three quarts of barley for a denarius, and do not harm the oil and wine!”
7 When he opened the fourth seal, I heard the voice of the fourth living creature say, “Come!” 8 And I looked, and behold, a pale horse! And its rider's name was Death, and Hades followed him. And they were given authority over a fourth of the earth, to kill with sword and with famine and with pestilence and by wild beasts of the earth. (ESV)