"Do not harm the oil and the wine" (oil and wine are for man's pleasure—Psa. 104:15—and are always in short supply and become precious in famine) signifies the presence of famine. War is always followed by famine. During the famine, oil and wine should be preserved and not harmed.
The fourth seal, consisting of a pale horse and its rider, signifies the spreading of death. Revelation 6:7-8 says, "And when He opened the fourth seal, I heard the voice of the fourth living creature saying, Come. And I saw, and behold, a pale horse, and the name of him who sits upon it is Death; and Hades followed him. And authority was given to them over the fourth part of the earth to kill with sword and with famine and with death and by the beasts of the earth."
Pale signifies the color of the appearance of those stricken with the plague.
Hades following death signifies that Hades receives and retains those whom death has killed.
Authority is given to Death and Hades over the fourth part of the earth to kill with sword, famine, and pestilence, and by the beasts of the earth.
The four riders of the four horses—the gospel, war, famine, and death—are all personified.