Window on the soul
The eyes, being amongst the most expressive of facial features, can reveal a lot about the way we feel toward a person. The way we look at them is an indication of how we intend to relate to them and that reveals as much about the state of our own soul as about the person we are looking at.
(Matt 6:22-23 WEB)6:22 “The lamp of the body is the eye. If therefore your eye is sound, your whole body will be full of light. 6:23 But if your eye is evil, your whole body will be full of darkness. If therefore the light that is in you is darkness, how great is the darkness!”
Good and evil eyes
In the Hebrew culture the eye was not something that took in light and converted it into what we see. Rather, the eye was like a lamp, it gave out. In English we preserve that sense when we speak about a person looking upon someone benevolently or about giving them the evil eye.
This section’s general theme is covetousness (the tenth commandment), so a sound eye is a generous one that does not covet others abilities or possessions. By contrast, an evil eye is one that looks greedily upon others wealth and status, wishing it was their own.
Jesus argues that the way we look upon others will colour all our dealings with them. If the way we look upon them is sound, then we will be full of godly wisdom (light) in dealing with them. However, if we look upon them the wrong way, then the advice we will offer is useless to see by (darkness), i.e. it is of no benefit in helping them to find the way of blessing that God has set before them.
...commentary continues with Matt 6:24