The word became flesh: the Son of God was veiled with human nature by being born of a woman (Galatians 4:4), like the children who were to become the sons of God (Hebrews 2:13-15), but when made flesh, he did not cease to be the Word of God.
Flesh points to man's weakness, for he appeared in the likeness of sinful flesh (Romans 8:3), and was crucified in weakness, in the flesh being made sin for us (2 Corinthians 13:4, 1 Peter 3:18, 2 Corinthians 5:21). By doing so, Christ became;
He dwelt among us: Dwelt is from skenoo meaning He pitched His tent among us (see also 2 Corinthians 5:1). He dwelt in this world till he had finished what he had to do here (chapter 17:4). He dwelt as in a tent, suggesting low circumstances (like shepherds), militancy (like soldiers), and a short passage. We are exhorted to "let the word of God dwell in us richly" (Colossians 3:16; Psalms 119:11).
We beheld his glory, the glory as of the only begotten of the Father: Christ was still the brightness of his Father's glory, even when he dwelt among us in this world. His disciples and followers, that spoke most freely and familiarly with him, saw and witnessed his divine glory, in His character and teaching, and in His actions and signs up to the time He ascended to Heaven (1 John 1:1-3). John in particular, together with Peter and James, witnessed His glory on the mount of transfiguration (Matthew 17:1-8; Mark 9:2-8; Luke 9:28-36).
Full of grace and truth: He had a fullness of compassion and a fullness of knowledge; he came to show us God's mercy, love, and forgiveness, and was fully acquainted with all he was to reveal. As we get to know Christ better, our understanding of God will increase.
John bore witness of him: this verse (15) is really a note and reads better if placed in parenthesis. John expressed his testimony loudly, in public, as one that was both certain of the truth to which he witnessed and was thrilled by it. He identified the Lord Jesus as the person he, as forerunner, had announced at the beginning of his ministry: He who had the precedency because, though born and appearing in public after him, existed before him. John the Baptist was to be called the prophet of the Highest whereas Jesus Christ was to be called the Son of the Highest (Luke 1:32). John was a great man, and had a great name and following, yet he was faithful enough to give the preference to Him to whom it belonged. He realised that Christ, as man, came after him but, as God, was before him by His eternal existence.
Of His fullness we have all received: Christ gave us - that is, to all who received him (v. 12) - all of His fullness of grace and truth (v.14). Everything we have received from Christ is summed up in this one word, grace: the unmerited good will of God towards us, and the good work of God in us.
Grace for grace: this expression is unusual, and therefore various interpretations are given of it:
The law was given through Moses: it was a perfect statement, both of God's will concerning man and His good will to man. However, it was also threatening, bound with penalties, bringing with it a curse, unable to give life (Galatians 3:10-12).
Grace and truth came through Jesus Christ: through His grace He redeemed us from the curse of the law, having become a curse for us (Galatians 3:13); the gospel of Christ has all the beneficial uses of the law, without the fear (Titus 2:11-14). He revealed to us the truth of God.
The only begotten Son ... has declared: we receive from Christ a clear revelation of God to us (v. 18), for He has declared that of God which no man had at any time seen or known (Ephesians 3:9); as the Son, He has always been in full communion with the Father (Matthew 11:27), with the exception of the very short time when He was made sin in our place (Mark 15:33-34).
And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth. (John 1:14)
John bare witness of him, and cried, saying, This was he of whom I spake, He that cometh after me is preferred before me: for he was before me. (John 1:15)
And of his fulness have all we received, and grace for grace. (John 1:16)
For the law was given by Moses, but grace and truth came by Jesus Christ. (John 1:17)
No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared him. (John 1:18)