What is the significance of saying that "the eye is the lamp of the body" (Matthew 6:22)?

from the old testament

• The eye being the lamp of the body is not found in the Old Testament, but it gives important background information that helps us understand Matthew 6:22. Job says, “I have made a covenant with my eyes” (Job 31:1). What you look at, desire, and set your attention on reveals and shapes what is happening in your heart and can lead to sin.
• Proverbs repeatedly connects the eyes with the heart and the path a person takes. Proverbs 4:25 says, “Let your eyes look directly forward,” connecting focused vision with walking on the right path. Proverbs 22:9 says, “Whoever has a bountiful eye will be blessed, for he shares his bread with the poor.” In contrast, Proverbs warns against an “evil eye” that is greedy and selfish (Proverbs 23:6–7; 28:22).
• When Samuel looks at Jesse’s sons, God tells him, “Man looks on the outward appearance, but the LORD looks on the heart” (1 Samuel 16:7). In Matthew 6:22 when Jesus says that "the eye is the lamp of the body," He is not merely talking about eyesight; He is addressing the inner orientation of a person’s heart.

from the new testament

• Matthew 6:22–23 falls within the Sermon on the Mount’s teaching on wealth and devotion. Just before it, Jesus said, “Do not lay up for yourselves treasures on earth … but lay up for yourselves treasures in heaven … For where your treasure is, there your heart will be also” (Matthew 6:19–21). Then, after the passage in question, He added, “No one can serve two masters … You cannot serve God and money” (Matthew 6:24).
• Given that Matthew 6:22–23 falls in the middle of this context, it seems likely that Jesus is referring to the same thing. However, it’s difficult for a modern reader to understand the connection. Those specific verses read, “The eye is the lamp of the body. So, if your eye is healthy, your whole body will be full of light, but if your eye is bad, your whole body will be full of darkness. If then the light in you is darkness, how great is the darkness!” (Matthew 6:22–23).
• Instinctively, people rightly recognize that Jesus was talking about the eye as illustrating one’s spiritual state. Less clear is how the eye as a lamp relates to the context of treasure and wealth. There are three interpretive views of this passage.
• First view—the eye as a source of light. This view builds on the idea that first-century people may have believed the eye was the source of light, rather than its passage. This view suggests that Jesus meant that a clear eye represents the ability to see God’s truth, while a bad eye represents one’s inability to understand it. While those concepts are biblical (cf. 2 Corinthians 4:4), it’s difficult to see how that interpretation fits in the passage’s flow.
• Second view—the eye reflecting one’s handling of money. This view tries to understand how the verses fit into the passage by saying that Jesus was saying that just as the eye affects one’s body, so also does how one handles finances affect one’s spiritual life. While a closer fit, contextually, Jesus was talking about one’s heart's devotion either to God or to wealth, not specifically about handling finances.
• Third view—Hebrew idioms. The third view has the strongest scholarly support. It argues that “good eye” and “bad eye” are Hebrew idioms that mean “generosity” and “stinginess,” respectively. If this view is correct, then it both fits the context and explains why it’s difficult for the modern reader to understand, yet perfectly understandable to the first-century hearer.

implications for today

This passage has proven difficult for modern readers because it’s difficult to understand how it relates to the surrounding context. However, as has also been said, it likely now involves obscured Hebrew idioms about one’s use of money reflecting the spiritual condition of one's heart. It thus aligns with the surrounding passages on being careful about what one treasures (Matthew 6:19–21) and serving God over wealth (Matthew 6:24).

Why are finances such a danger area? Because money brings security. It’s because of security that we save for retirement, purchase life insurance, and develop our skills to increase our paychecks. Money brings security. But that security comes with the temptation of trusting it instead of trusting God.

People experiencing poverty often think that if they just get a little more money, then they will be happy. But just look around. The world is full of wealthy people who are still looking for “just a little bit more.”

This was Jesus’ concern: our desire for security in money leads us to worship it. He was saying that when we grab onto wealth so tightly, making it our life raft, it, and not God, has become our god. We can’t serve both God and money.

Consider your own finances. God isn’t necessarily calling you to be poor, but are you using what He has given you to help your church and others? Are you willing to help someone in need—using wisdom as to who truly has a need—or are you content with saying “be warm and filled” (James 2:15–16)?

How you use your excess wealth is between you and God (and your spouse if you are married). Consider how you might better steward your money, demonstrating that you trust in Him rather than in your bank balance.