|Zuraban, Agnus Dei|
Prologue (the Logos Hymn; 1:1–18)
The Book of Signs (1:19–12:50)
• Initial Days of the Divine Revelation (1:19–51[2:11])
• First to Second Cana Miracle (2:1–4:54, Overlaps with Initial Days)
• Jewish Feasts and Their Replacements by Christ (5:1–10:42)
• Raising of Lazarus and its Aftermath (11:1–54)
• Conclusion to the Book of Signs: Jesus Prepared for Passover (11:55–12:50)
The Book of Glory (Passion and Resurrection Narratives; 13:1–20:31)
• the Last Supper (13:1–17:26)
• The Passion (18:1–19:42)
• The Resurrection (20:1–29)
• Conclusion to the Book of Glory: Statement of the Author’s Purpose (20:30–31)
John 1:35–51 falls into what I call, the Initial Days of the Divine Revelation (1:19–51).
• John as a Witness (1:19–34)
◦ Concerning His Own Mission (1:19–28)
◦ Concerning Jesus (1:29–34)
• The Baptist’s Disciples Come to Jesus (1:35–51)
◦ Andrew and “another” (1:35–40)
◦ Simon Peter (1:41–42)
◦ Philip and Nathanael (1:43–51)
That whole section really should be read together, because just starting with v. 35 might lead a reader into missing the fundamental difference between the Johannine depiction of JBap and the Synoptic. John the Baptist in John never actually baptizes Jesus! It is implied, to be sure, but JBap's role in the Fourth Gospel is primarily as a witness, and what we see in vv. 35–51 is simply the disciples' handing off that initial witness.
Concerning JBap's witness of Jesus, note that twice he calls him "The Lamb of God" (1:29, 36). The first time he proclaims, "Behold the Lamb of God, which taketh away the sin of the world." To understand Johannine soteriology, make sure to read that as sin singular. I cannot tell you how many times in performing Handel's Messiah I need to correct my fellow singers, who sing "sins of the world" out of habit or lack of understanding.
Regarding the "chain reaction" of witnesses . . . note that JBap bears witness to Andrew and "another" (usually assumed to be John). Andrew finds Peter. Peter finds similarly Greek-named Philip. Finally Philip finds Nathanael. Also note that there is no Marcan "messianic secret" here. Andrew tells Peter in 1:41 that they have found the Messiah, or Christ, a title that does not appear in Mark until 8:29. Philip tells Nathanael that they have found the one foretold by Moses. And when Jesus tells Nathanael that he had "foreknown him," Nathanael calls him the Son of God in 1:49.