The Light of the world

1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was in the beginning with God. 3 All things were made through him, and without him was not any thing made that was made. 4 In him was life, and the life was the light of men. 5 The light shines in the darkness, and the darkness has not overcome it.
6 There was a man sent from God, whose name was John. 7 He came as a witness, to bear witness about the light, that all might believe through him. 8 He was not the light, but came to bear witness about the light. 9 The true light, which gives light to everyone, was coming into the world (Jn 1:1-9).

V9 is a tricky passage:

1. The syntax is ambiguous. Does the light illuminate everyone coming into the world, or is the light which illuminates everyone coming into the world? 

2. In what sense does Jesus illuminate everyone? Here we have a double entendre. 

i) On the one hand, the narrator identifies Jesus as the lightgiver in the creation account (Gen 1). "Let there be light!" That refers to physical light. Sunlight, moonlight, and starlight. That kind of light is universal. Everyone is illuminated by daylight. By creating the luminaries, Jesus "enlightens" every earthling. 

ii) On one rendering of v9, this means the source of daylight is now coming into the world via the Incarnation. The Creator who, in the past, has been the source of universal illumination (i.e. sunlight, moonlight, starlight) is now coming into the world. The illumination has been ongoing since the world was made. What is new is his entrance into the world.

iii) On another rendering of v9, everyone who is born enters into this ongoing process. It was happening long before they were born. In birth, they now share in the status quo.

iv) In that sense, the light is universal because it denotes literal daylight. Other than the blind, everyone has an experience of light in that sense.

v) But in addition, narrator uses light as a theological metaphor. In that sense, the scope of the light is not universal. Rather, it refers to the revelation of the Incarnate Son, during his public ministry. That has a point of origin at a particular time and place. Insofar as people are exposed to the light in that sense, they react one way or the other (Jn 3:19-21). 

Over time, the scope of the light, in that figurative sense, becomes more extensive through evangelism. It begins to penetrate the dark corners of the world, as missionaries bring the Gospel to far-flung parts of the globe. In that respect, the illumination is progressive. 

vi) In neither sense does it refer to inner illumination or general revelation. Literally, it refers to daylight. Figuratively, it initially refers to the public ministry of Christ, and subsequently to evangelism.