The eyes are the windows of the soul, they say – a folk saying that may have been around when Jesus taught his seminar on the mount:
‘The eye is the lamp of the body. So, if your eye is healthy [literally single], 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).
Our modern Western brains may need re-educating to be able to understand the biblical significance of these metaphors and their practical intention for our day to day living.
‘The evil eye’
In pirates’ tales ‘the evil eye’ implies a bewitching curse flung upon the victim by some hateful enemy. But Jesus was using a term familiar to his listeners for a stingy person (see Matthew 20:15 margin (Greek). For instance, an Israelite may be tempted not to lend to a poor neighbour because the sabbatical year for obligatory debt cancellation is so close:
‘If among you, one of your brothers should become poor … you shall not harden your heart of shut your hand against your poor brother. …Take care lest there be an unworthy thought in your heart and you say, “The seventh year, the year of release is near” and your eye look grudgingly [margin, be evil] on your poor brother, and you give him nothing, and he cry to the Lord against you, and you be guilty of sin. You shall give to him freely and your heart shall not be grudging [margin be evil] when you give to him, because for this the Lord your God will bless you in all your work and in all that you undertake’ (Deuteronomy 15:7-10).
See also Proverbs 28:22, where ‘a stingy man’ is ‘a man whose eye is evil’ (Hebrew, margin). And earlier in Proverbs is this classic piece:
‘Do not eat the bread of a man who is stingy [margin ‘whose eye is evil]; do not desire his delicacies, for he is like one who inwardly is calculating. “Eat and drink!” he says to you, but his heart is not with you. You will vomit up the morsels that you have eaten, and waste your pleasant words’ (Proverbs 23:6-8)
King Saul’s son Jonathan, after a day on the battle field with no time for food, on finding a wild bees’ nest, poked it with his staff and boosted his blood sugar levels on the honey – ‘and his eyes became bright’ (1 Samuel 14:27). And Ezra prayed that ‘our God may brighten our eyes and grant us a little reviving in our slavery’ (Ezra 9:8).
 The means of brightening one’s eyes is by the countenance of the Lord (see Psalm 4:6-8) and his commandment (Psalm 19:8; compare Psalm 119:135).
 The result of brightening of one’s eyes is reviving of one’s spirits (Psalm 13:3) and even motivation for reconciliation of estranged relationships (Proverbs 29:13).