There are two types of light in the world. We can be aware of and comprehend one, or both, or neither. When we are born, most of us immediately become aware of physical light. As we develop, by that natural physical light, we see and learn about God's beautiful creation.
And although that light is good and necessary for physical growth and health, there is another light in the world that enables us to know God. In the Old Testament, that light shone from time to time as men would earnestly seek Him and as He honored their hunger by revealing more of Himself to them.
How many times have you gotten up from bed in the middle of the night and hit your leg or stubbed your toe on some obstacle you couldn't see because of the darkness? We all have at one time or another. Or perhaps you have spent a night in fear of some danger, whether real or imaginary, because it was dark. How different everything seemed the next day in the bright sunshine!
It's easy to understand how the analogies of darkness and light can be used as symbols of evil or good, error or correctness, uncertainty or assurance, trouble or peace, death or life. Black, or the dark, represents everything bad in the world, and light is a symbol of all that is good.
Contrary to popular thought, dark is not the opposite of light. Darkness is the absence of light. Think about it. You can be in a totally dark room, but when someone strikes a match or turns on a flashlight [torchlight], immediately the light invades the darkness. And no matter what happens, darkness never gets more dark  pitch black is simply pitch black. But light, on the other hand, can get brighter and lighter. Darkness can never overcome light either, but the light can totally repel the darkness.
Without God in our lives, all we can do is wander around in the dark  lost, not knowing where we are going, searching for a light, for a reprieve, for a way out . . . for a way back to Him for whom we were created.
The light spoken of above is so necessary to our souls that the Son of God became one of us to declare it and to impart it to us, so that by it, we might better know our God.
Until we receive a special revelation of the true Light of God, we are all in spiritual darkness headed for certain destruction where "there will be weeping and gnashing of teeth" (cf. Matthew 8:12, 13:42,50, 22:13, 24:51, 25:30; Luke 13:28).
That is why Jesus describes Himself as the "Light of the World"; He came to give us God's light, to reveal to us God's love and His will for us.
Listen to Jesus' own words about Himself.
It's a reality of nature that light totally, absolutely repels [drives away] darkness! Where there is light, no darkness remains.
In the same way as natural light repels natural darkness, Jesus, the Light of the world, drives out the spiritual darkness that came as a result of man's sin. His presence in our hearts repels sin, guilt, shame, and fear. His love drives out hatred and brings hope, assurance, comfort, and strength to the soul.
In a way, you could say that light is stronger than darkness. All the darkness in the world can't shut out the light of a single candle. If you have Jesus in your life, the powers of evil around you and the dark experiences of life cannot put out His light.
Frances Jane Crosby (1820–1915), better-known as Fanny Crosby, was one of the most prolific hymn writers in history. Despite being blind since the age of six, Fanny Crosby wrote more than 8,000 hymns. She did not spend her life in bitterness and defeat, but instead dedicated her life to Christ.
She once remarked that, if she had perfect earthly sight, she might not have written so many poems and hymns to the Lord because she'd have been distracted by all the interesting things in this world. But in blindness, she could "focus" on the pure light of God. She said, "When I get to Heaven, the first face that shall ever gladden my sight will be that of my Savior!" Jesus was clearly her inner source of spiritual light that drove away the darkness and gloom. He flooded her soul with sunshine. Although she didn't have the first natural physical light we mentioned in the introduction, she certainly perceived the second Light!
Often, things in the dark take on peculiar qualities or shapes  sometimes as a result of varying shadows and other nearby objects and sometimes from our own active imaginations. But in the light we are able to see these objects as they truly are. In the same way, spiritual light reveals the truth about God, His will and His works, and it exposes the works of darkness done by our spiritual enemies.
We find this light in God's written Word, the Bible, and in God's living Word, Jesus Christ. As the Creator, Jesus is also the revealer and interpreter of life. He helps us understand God's Word and shows us God's way for us. He, Himself, is the way.
Jesus helps us to see ourselves as we really are. In the light of His perfect life and teachings and what He reveals to us about God the Father, we see how far short we come of God's standards and requirements. We see our sins, our pride, our self-centeredness, and hidden motives. Jesus shows us our need for the forgiveness and new life that only He can offer us.
In Jesus we see God's love for us, His patience with us, and His provision for our salvation. He shows us how to receive God into our lives and enjoy His light forever.
Light is also radiant energy. As scientists are learning more about the power of light radiating from the sun, we see more and more building and inventions that utilize solar energy.
The sun's energy is a tremendous source of power for human use. We can use it to heat our homes and power some machines.
But greatest of all is its effect on organic life and health. Plants need sunlight in order to grow. Sunlight also kills many germs and contributes to our health and strength. Plants are positively phototropic [they are always drawn to the light]. They will never draw away from the light. In fact, if you have a plant that is drooping on one side, turn that side toward the light and watch as the plant gains strength and actually turns itself to the light.
What the sun is to the earth and the other planets that share our solar system, Jesus, the "Sun of Righteousness", is to us.
Just as the sun produces life, health, warmth, energy, and power to the earth, Jesus Christ brings life, health, warmth, energy, and power to those who accept Him. And like the plant bursting forth from the seed and rising to meet the sunlight, the dead in Christ will one day burst forth from the grave with new bodies and rise to meet the "Light of the World" when He returns for them.
Light does not discriminate. It shines where it shines and everything within its path equally receives the light. The sun shines on the rich and the poor, the wise and the foolish, the tall and the short, the weak and the strong, the fair-skinned and dark-skinned. Light simply does not care who or what it shines on. It simply shines.
When Jesus was walking with a group of followers one day, a blind man sat by the roadside begging. He had heard about Jesus' power to heal, and he cried out with a loud voice, "Jesus! Son of David! Have mercy on me!" (Mark 10:47) The people scolded him and told him to be quiet because they didn't think Jesus had time to help a beggar. But Jesus not only had time for that one man, and countless others during His earthly ministry, but He has time and help for everyone who calls on Him in faith!
Life took on new meaning and a new direction for that man that day. Light had suddenly invaded his world of darkness. And just as suddenly, the past no longer mattered; it didn't matter what he had been, where he'd sat begging, how he had stumbled in the dark. Now he walked in the light!
Drive down a dark alley at night and watch what happens as the light from your vehicle's head lamps falls on the "inhabitants" of that alley. Rats, street dogs and alley cats scramble under the dumpsters and behind boxes to escape the light. Drunkards turn their heads away and hold up their hands to try to block the light from their faces. Homeless people pull their meager coverings over themselves so as not to be seen.
In much the same way, some people refuse, and even try to escape, the light Jesus wants to bring into their lives. They want to continue living like they have, to have their own way. They don't want God on His terms; they want Him on theirs.
And neither will man's rejection of Christ today put out the light. Jesus told the people of His day that He had brought salvation for everyone. And He makes the same promise for us today. Whoever accepts Him will be saved. But those who refuse His light are condemning themselves to live in darkness and to one day be cast into a place Jesus called "outer darkness where there will be weeping and gnashing of teeth"!
For believers, Jesus promises that we will never walk in darkness (cf. John 8:12), which is a reference to the assurance of salvation we have in Him. He also promises that, as long as we remain in the Light, we will not habitually sin. Instead, we repent of our sin in order to stay close to the Light of His love.
The moon has no light of its own, but rather reflects the light from the sun. Jesus says that we also will reflect His Light into our dark world. In fact, He commands that we be lights. "You are the light of the world. A city set on a hill cannot be hidden. Nor do people light a lamp and put it under a basket, but on a stand, and it gives light to all in the house. In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven." (Matthew 5:14-16) Of course, the way in which we reflect His light is by our actions and our words.
It is important that we, as believers in the Lord Jesus Christ, maintain a consistent, credible, and obvious witness in the world by honoring God in all that we do. And we should always be "prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect" (1 Peter 3:15), so that others living in spiritual darkness might come to the Light.