Matthew 6:23 But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!
But, on the other hand, if your eye is diseased or blind, the whole body shall be dark or filled with darkness. If then the illumination that is in you is, in fact, darkness, or ignorance of spiritual things, how great that darkness is!
This illustration is a metaphor of the eye being the light of the body, or the place where light enters in. We could think of the eye as the window of the body, and it would reasonably fit into this comparison.
Jesus says that If the eye is healthy and sound, then the body shall be full of light, but if the eye is diseased or blind, then there is only darkness in the body.
The word darkness used in the latter part of verse 23 is from a Greek word defined in Strong’s Concordance firstly as darkness of night or of blindness, but secondarily it is defined as figuratively speaking of the “ignorance respecting divine things and human duties, and the accompanying ungodliness and immorality, together with their consequent misery in hell.”
It seems clear that Jesus is referring to this type of darkness, since the physical body does not actually fill up with natural light. He’s using an analogy, a parable, and He is talking about the inward man, the hidden man of the heart, the inside of a person, the spirit of a person, being filled with either understanding or ignorance of spiritual truth, or light.
The Healthy and the Diseased Eye
In this example, the healthy eye represents the heart that desires to learn and grow in spiritual truth, which is the true light. That heart looks for and pursues light. The evil or unhealthy eye represents the heart that has no desire or hunger for spiritual truth, the result being a heart filled with darkness, a heart fille with ignorance of spiritual realities.
This person, however, believes that he has light, he believes that he has understanding, but the light he believes himself to have is, in fact, darkness, or ignorance of the spititual truth.
John 3:19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.
John 3:20 For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved.
John 3:21 But he that doeth truth cometh to the light, that his deeds may be made manifest, that they are wrought in God.
Come to the Light
Light has come into the world, spiritual light, spiritual illumination, through Jesus Christ, who is Himself the light of the world. But it says that men loved darkness rather than light because their deeds were evil, and they would not come to the light and receive true understanding. The one who loves evil will not come to the light, he will not go near the light, lest he be exposed.
But the one who does truth, the one who is a doer of the word of truth, he comes to the light that Jesus gives, that it may be made clear and evident that his deeds are performed in God, for the one who walks in light walks with God.
Children of Light Ephesians 5:8 For ye were sometimes darkness, but now are ye light in the Lord: walk as children of light: Believers in Christ are the children of light. As children of light, let us have a single eye, a healthy eye, a heart that pursues the light of God’s truth and walks in that light day by day, being doers of the truth, and being filled with the light of God.