John 1:4

". . . we move on from creation in general to the creation of life, the most significant element in creation. Life is one of John’s characteristic concepts: he uses the word 36 times, whereas no other New Testament writing has it more than 17 times (Revelation; next come Romans with 14 times and 1 John with 13 times). Thus more than a quarter of all the New Testament references to life occur in this one writing." [Note: Morris, p. 73.]

Jesus was the source of life. Therefore He could impart life to the things He created. Every living thing owes its life to the Creator, Jesus. Life for humankind constitutes light. Where there is life there is light, metaphorically speaking, and where there is no light there is darkness. John proceeded to show that Jesus is the source of spiritual life and light as well as physical life and light (cf. John 5:26; John 6:57; John 8:12; John 9:5; John 10:10; John 11:25; John 14:6; John 17:3; John 20:31). Metaphorically God’s presence dispels the darkness of ignorance and sin by providing revelation and salvation (cf. Isaiah 9:2). Jesus did this in the Incarnation.