The Tabernacled Word

John's gospel or good news testimonial to Jesus' person and nature is summarized in this key verse: And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. (John 1:14 ESV)
Who is this Word? What is the nature and purpose of his coming? To fully grasp the meaning of this sentence we must consider the context. The context constitutes verses 1 through 18 which we call his Prologue, "the word before the word" that sums what the writing that follows consists of and serves as an introduction to its layout.