The first words of John's Gospel echo Genesis 1. In the beginning was the Word. Before anything was made, the Word was with God and was God. All things were made through Him. Just as God spoke light into being at creation, the Word brings life and light into a dark world. The darkness hasn't overcome it.
Then John tells the most amazing news. The Word became flesh, and lived among us. The eternal Son of God took on a human body and moved into our neighborhood. Not everyone welcomed Him. But to all who received Him, He gave the right to become God's children, born not of human will, but of God. From His fullness we all received grace upon grace. The law was given through Moses. Grace and truth came through Jesus Christ.
John the Baptist knew his role. He was not the light, but a witness to the light. He pointed to Jesus and said, Behold, the Lamb of God. A lamb was used for sacrifices, so this title pointed to Jesus' death for sin. The first disciples followed Jesus one by one. Andrew brought Simon. Philip brought Nathanael. When Nathanael doubted, Philip simply said, Come and see. Nathanael met Jesus and confessed Him as the Son of God and King of Israel.