Students often ask me about a saying from Jesus’ Sermon on the Mount: “… if your eye is good, your whole body will be full of light; but if your eye is bad, your whole body will be full of darkness” (Matthew 6:22-23). It’s an interesting saying to study, because it requires us to look carefully at the context, at the Old Testament background, and at some unusual Greek and Hebrew idioms. More importantly, once the passage is understood clearly, it illuminates a key kingdom principle.

First, we need to look at the two key phrases that make Jesus’ saying so mysterious. The evidence is good that “evil eye” (Greek ophthalmos poneros) refers to stinginess or greediness. Jesus later uses the phrase to describe the laborers in the vineyard who begrudge full pay to those who work less (Matthew 20:15).  The Old Testament warns against the man with an “evil eye” (Hebrew raa ayin), who is selfish and greedy (Proverbs 23:6, 28:22). The Law commands the person with wealth not to have an “evil eye” and thus withhold help from a needy brother (Deuteronomy 15:9).

In contrast, “good eye” (Greek ophthalmos haplos) refers to generosity. Although haplos (and its cognate forms, haplous and haplotetos) can also refer to singleness or simplicity, neither of those meanings makes as much sense in this context. The haplos word group is used to refer to generosity several times in the New Testament (Romans 12:8, 2 Corinthians 8:2, 9:11, 9:13, James 1:5). A parallel idiom is found in the Old Testament: “He who is generous (Hebrew tov ayin, good eye) will be blessed, for he gives some of his food to the poor” (Proverbs 22:9; see also 11:25).

So Jesus’ saying is an invitation to choose generosity over stinginess. It interacts with and informs Jesus’ teaching in Matthew 6 about the giving of alms (a key act of piety in first-century Judaism). Jesus transforms almsgiving: generosity should be secret, so that it is for God, not humans (6:2-4); generosity is like making a deposit in heaven (6:19-21); generosity lights up our whole lives (6:22-23); we must choose God as master, not money (6:24); and we must avoid worry so that we can be generous (6:25-34).

For some reason, people often overlook this key theme of generosity in Matthew 6. They think Jesus was talking about tithing (he wasn’t!), and they read the passage on worry without noticing its connection to the command to be generous. Jesus’ “good eye” teaches that generosity to the needy brings light to our lives, makes a deposit in heaven, and demonstrates that God is our master.