He was not that Light, but was sent to bear witness of that Light.
He was not that Light [rather, 'The Light' to (G3588 ) Foos (G5457 )], but [was sent] to bear witness of that (or 'The') Light. Noble testimony this to John, that it should be necessary, or even pertinent, to explain that he was not The Light! But John found it necessary himself to make this disavowal (John 1:19-21); and certainly none could be more deeply penetrated and affected by the contrast between himself and his blessed Master than he (See the notes at Luke 3:15-16; and at John 3:27-34.) From the very first he saw and rejoiced to think that his own night-taper was to wax dim before the Day-spring from on high (John 3:30).