John 1:18

God the Father never reveals Himself to men directly, but always by and through His only-begotten Son. This was the case even before the Incarnation. It was God the Son who manifested Himself to the patriarchs, gave the Law to Moses, inspired the prophets, and enlightened the sages of the Gentiles. But now by His Incarnation He has revealed God more perfectly. So completely does 'the Word made flesh' represent the invisible Father, that 'he that hath seen me hath seen the Father' (John 14:9): cp. John 5:37; John 6:48; Exodus 33:20; Colossians 1:15; 1 Timothy 6:16; 1 John 4:12; 1 John 4:20. The only begotten Son] Many very ancient authorities read, '(the) only begotten God,' a striking statement of our Lord's Deity. In the bosom] i.e. in eternal, intimate, loving union with the Father: cp. the expression 'in Abraham's bosom' (Luke 16:22), and John 13:23. This v. explains how it is that God is love, not only since the creation, when He created objects for His love, but from eternity: cp. John 17:24.

John 1:19 to John 4:42. Preliminary ministry of our Lord. All the events recorded by St. John from John 1:19 to John 4:42; (the testimony of the Baptist; the preliminary call of John, Andrew, Peter, Philip, and Nathanael; the marriage at Cana; the visit to Capernaum; the first cleansing of the Temple; the interview with Nicodemus; the interview with the Samaritan woman) may be regarded as a preliminary ministry, for they took place before the Baptist was cast into prison (see Matthew 4:12). The ministry proper begins with the imprisonment of the Baptist, upon news of which Jesus withdrew into Galilee (Matthew 4:12; John 4:43; John 4:46).