“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. 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. And when he had opened the fourth seal, I heard the voice of the fourth beast say, Come and see. 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.” Revelation 6:5-8
In this verse John writes that he heard what seemed to be a voice coming from the midst of the four living creatures (Revelation 4:6–8). The voice announced that a quart of wheat was selling for a denarius and three quarts of barley cost a denarius. Symbolically, this passage seems to indicate a common experience in real-world crises: war and famine give way to inflation due to supply and demand.
A denarius in the first century was usually equal to a day's wages, and the amount of grain given here is just enough to keep a person alive. These are also the commodities of the common person: basic staples for living. The implication seems to be that most people in this part of the tribulation are struggling just to meet their basic survival needs. This is the kind of poverty which threatens a person's life, not merely their lifestyle.
However, the voice from the midst of the four living creatures also commanded, "Do not harm the oil and wine!" Oil and wine, in this context, are less crucial supplies, making them a form of minor luxury. The implication that these are not harmed might suggest that wealthy people would not be hurt by the economic or inflationary catastrophe. According to Revelation 13:16–17, the false prophet in Jerusalem will control commerce during the tribulation, making it extremely difficult for tribulation believers to purchase even basic commodities.