This chapter contains an account of the opening of six of the seven seals. The scene opens into the future of things - at least the future to John. The actors in this final drama are the Son of God, angels, men, Satan, storms, tempests, earthquakes, pestilence and fire; the scene is heaven, earth, and hell. Revelation mentions no names or times that allow us to pinpoint everything down to a specific time and place. And since the future is "boundless" there are boundless interpretations.
The Lamb, the worthy one, opens the first seal and shows John that which was to come to pass. He looked and saw this and then first heard something - one of the four beasts spoke and it's voice was as thunder. The only beast this first one could be would be the described as the - Lion beast. The Lion represented the Lion of the Tribe of Judah, or perhaps the arrival of the promised Messiah and His ministry. It seems that John was seeing some sort of pictorial or vision of the events he was describing. And he saw a "white horse." In scripture horses are emblematic of war or battle. Each of the four horses we will read about have varying colors: white is purity, red is blood shed, black is corruption and pale or gray is death and ash. In terms of the last days of the age of the Jew, we might see the white horse as the arrival of the only true Messiah on the scene, riding in to conquer sin and death, with a bow in His hand and a crown on His head.
Now we read about the second seal being opened and the horse that came into the scene as a result was a red horse rider and the power and sword he possessed, of course, is indicative of war. Jesus, the Prince of Peace, wearing a crown and bearing a bow, went out on a white horse to conquer on the first broken seal and next came a rider on a red horse who was given power to "take peace from the earth." As the white horse denoted prosperity, triumph, and happiness, this red horse would denote carnage, discord, and bloodshed. This is a clear description of the warfare that was about to fall upon Jerusalem.
Then the black horse that enters the scene is an emblem of famine, which many believe took place under the Roman Emperor around 50 AD. While famine fell upon the land there was neither wine nor oil that was effected. Perhaps the symbolism in scripture of wine (the blood of Jesus) and oil (Holy Spirit) spared those who were blessed from the effects of the black horse curse.