In Him was life, and the life was the Light of men. John 1:4
Everyone who is alive at all has the breath of life in them. Even microbes are alive. In a different sense all people are alive. However, there is a unique sense of the word “life” that was in Him that was not in men, or else there would be no sense in saying this. There is some sense in which men are in darkness as pertains to this sense of the word life, and so this life is unique to Him.
In another sense, the Greek way of thinking about the logos is that it is not alive, it is an impersonal force. Scientists even now are not looking for a designing intelligence, a living creative mind, at the root of existence. They are looking for impersonal forces and principles. However, they are looking for the wrong thing, because the logos has personality, and in Him is life. Life, not lifelessness, is behind the structure and direction of the universe.
Also, there is the inference that the things thus far — God, Word, personality, creation — are not apprehended by men. They are not the light of men because they are not seen or grasped by men. In a way men are in darkness because men have never really encountered the true God. However, this life is the light of men: they have now seen Him. So this is not light in the sense of Genesis 1, it is light which men perceive. It is the light of men. These other things may seem to be abstract musings to men, but they are hidden. No one has seen God (John 1:18) but the only begotten God (what a phrase!) who is in the bosom of the Father (again — wow!) has explained Him. Moses’ miracles are little magic tricks in comparison to this: God Himself has incarnated and walked among us, and has died for our sins. Jesus Christ is the radiance of His glory and the exact representation of His nature (Hebrews 1:3).
I think another sense in which He is the light of men, is that His very life represents the perfection of the law. He not only taught the perfection of the law, as in the sermon on the mount, but He lived perfectly according to the law, all the way to the death. He is, in word and deed, like a flashlight that is able to look beyond our pretense of righteousness and significance, to see our true disease. We think we do not need forgiveness, we do not need to be saved. We think we are just on the cusp of lasting reform. We think our sins are small and insignificant while our righteous deeds are weighty and significant. When we encounter the living Christ, we can see ourselves for the dead husks we are, and cry out for authentic living.
Finally, the logos life which is the light of men is light to men because He offers true reconciliation with the living God through His death and resurrection. In Him we have newness of life (Romans 6:4) because as He was raised from the dead, we too have newness of life. We see all the ragamuffins and riffraff, the sinners and prostitutes and tax-gatherers, flock to Him because He offered life first, and through this unconditional offer of eternal life, a new kind of repentance. Through the light of His perfect keeping of the law, and our thorough condemnation through this, we are able to receive the free gift of life in Him. So I think perhaps we can think that “the Light of men” is His perfect keeping of the law, and that “life” indicates justification and salvation.
The Light shines in the darkness, and the darkness did not comprehend it. John 1:5
We have the idea here that the light is not contained or withheld or kept secret, but shines or spreads into places where it is not.
Darkness is personified as being possibly able to apprehend or comprehend the light, but does not. Possibly the darkness could seen as meaning men, since they in need of a unique kind of life which the Word possessed but they did not. It can be deduced from observing these two verses that light is lacking in men and so this deficiency of life and light in men is the darkness the light is shining into. This is corroborated by the apostle’s writing in 1 John:
We know that we have passed out of death into life, because we love the brethren. He who does not love abides in death. 1 John 3:14
8 On the other hand, I am writing a new commandment to you, which is true in Him and in you, because the darkness is passing away and the true Light is already shining. 9 The one who says he is in the Light and yet hates his brother is in the darkness until now. 10 The one who loves his brother abides in the Light and there is no cause for stumbling in him. 11 But the one who hates his brother is in the darkness and walks in the darkness, and does not know where he is going because the darkness has blinded his eyes. 1 John 2:8-11
So we know that in John’s mind darkness and death are related to men who hate, while light and life are related to faith and love. This means that darkness isn’t just being personified, it actually signifies the state of rational men who hate and abide in death. The way of living and thinking of unbelieving men is the darkness, and they do not comprehend the light. They speak from and listen to the spirit of error, not the spirit of truth (1 John 4:6). These people are what he calls “darkness”, and these people are the ones who do not comprehend the light of Christ.