Akagi, Kai. "The Light from Galilee: The Narrative Function of Isaiah 8:23-9:6 in John 8:12." Novum Testamentum 58 (2016), 380-393.
Akagi considers the context of John 8:12 in the overall flow of chapters 7-8 and concludes that it uses an allusion to Isaiah 8:23-9:6, in the Septuagint numbered 9:1-7, to answer the objection of John 7:52 (Akagi 2016, 380). He briefly surveys interpretations which have suggested the verse as an allusion to some external source. The imagery of light and darkness is very common in the Old Testament and is not uncommon in early Christian sources. However, a purpose for placement at 8:12 has not been widely studied (Akagi 2016, 382).
Akagi observes the Pericope Adulterae, which he considers a later insertion, may obscure the context of verse 12 as a continuation of the material found in John 7 (Akagi 2016, 383). 8:12 may easily be understood as recalling the language of Isaiah 9:1 and, when the Isaianic context is taken into acount, make a strong argument for Jesus' identity as the Davidic Messiah who needs to come from Galilee. Akagi surveys a variety of commentaries and articles which suggest the relationship but fall short of affirming it (Akagi 2016, 384). John's frequent use of Isaiah may strengthen the case for an allusive statement (Akagi 2016, 385).
In John 7:52 the Pharisees had asserted that no prophet arises from Galilee (Akagi 2016, 387). Akagi consiers how parts of 8:12 could be more easily understood if the verse is seen as an allusion to Isaiah. The words "then again" are well seen as referring to some event or statement being continued. This would logically include the statement of the Pharisees (Akagi 2016, 388). Yet Akagi finds many commentators who do not identify a connection. The scorn of the Pharisees for Galilee is striking to Akagi. Therefore he considers it likely to influence other statements in proximity to the end of John 7 (Akagi 2016, 389). Al allusion to Isaiah and the need for the Messiah to come from Galilee both erodes the credibility of the Pharisees' argument and reinforces the role of Scripture in affirming Jesus as the Messiah. Jesus' opponents demonstrate that they don't understand the Scriptures (Akagi 2016, 390).
In sum, Akagi finds that John is identifying Jesus not only as a prophet, but "the" prophet, the coming Messiah. This knowledge eludes the Jewish leaders, but it is made known in the Gospel (Akagi 2016, 391-392).