The first part (verses 1-18) is an introduction to the Gospel as a whole, stating that the Logos is "God" (divine, god-like, a god according to other translations) and acts as the mouthpiece (Word) of God "made flesh", i.e. sent to the world in order to be able to intercede for man and forgive him his sins (The Good News of the Gospel). This portion of John's gospel is of central significance to the development of the Christian doctrines of the Trinity and the Incarnation.
Comparisons can be made between these verses and the narrative of Genesis 1, where the same phrase In the beginning first occurs along with the emphasis on the difference between the darkness (such as the earth was formless and void, Genesis 1:2) and the light (the ability to see things not understood/hidden by the darkness, John 1:5). John Wesley summarised the opening verses of John 1 as follows:
1 In the beginning was the Word, and the Word was with God, and the Word was God.
2The same was in the beginning with God.
3All things were made by him; and without him was not any thing made that was made.
According to the writers of the Pulpit Commentary, the phrase "the light of men" (John 1:4) "has been differently conceived by expositors.
Calvin supposed that the "understanding" was intended - "that the life of men was not of an ordinary description, but was united to the light of understanding," and is that by which man is differentiated from animals. Hengstenberg regards it, in consequence
of numerous associations of "light" with "salvation" in Holy Scripture, as equivalent to salvation; Luthardt with "holiness" and many with the "eternal life," which would introduce great tautology." English translations of John 1:5 variously translate the Greek
Κατελαβευ as "understanding" (e.g. the New King James Version: "the light shines in the darkness, and the darkness did not comprehend it"), but in other translations the meaning
is given in terms of a struggle between darkness and light: "the light shines in the darkness, and the darkness has not overcome it" (Revised Standard Version). Verses 10 and 11 state that "He was in the world, and the world was made through Him, and the world did not know Him. He came to His own, and His own did not receive Him" but theologians differ in their interpretation of these verses. Wesley viewed "in the world" as meaning "even from the creation", the Pulpit Commentary speaks of the "pre-Incarnation activity" of the Word and Joseph Benson wrote that "He was in the world … from the beginning, frequently appearing, and
making known to his servants, the patriarchs and prophets, the divine will, in dreams and visions, and various other ways", whereas in Albert Barnes' opinion, "He was in the world … refers, probably, not to his pre-existence, but to the
fact that he became incarnate; that he dwelt among human beings".
6 There was a man sent from God, whose name was John. 7The same came for a witness, to bear witness of the Light, that all men through him might believe. 8He was not that Light, but was sent to bear witness of that Light.
9 That was the true Light, which lighteth every man that cometh into the world. 10He was in the world, and the world was made by him, and the world knew him not. 11He came unto his own, and his own received him not. 12But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: 13which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
15 John bare witness of him, and cried, saying, This was he of whom I spake, He that cometh after me is preferred before me; for he was before me.
16And of his fulness have all we received, and grace for grace.
The summation of the comparison between darkness and light occurs in the statement, the law was given through Moses … grace and truth came through Jesus Christ (John 1:17). Here John successfully bridges the gap for the reader - including
Jewish readers well-versed in the Torah - from the Law to the One who would fulfill the Law (such as the requirement of animal sacrifice for the forgiveness of sins, Hebrews 9:22), Jesus.
Commentary from Wikipedia · Hamlet · John 1 · The Starry Night