Mark John's clear apprehension of the limitations of his work. He
baptized with water, the symbol and means of outward cleansing. He
does not depreciate his position or the importance of his baptism,
but his whole soul bows in reverence before the coming Messiah,
whose great office was to transcend his, as the wide Mediterranean
surpassed the little lake of Galilee. His outline of that work is
grand, though incomplete. It is largely based upon Malachi's closing
prophecy, and the connection witnesses to John's consciousness that
he was the Elijah foretold there. He saw that the Messiah would
surpass him in his special endowment. Strong as he was, that other
was to be stronger. Probably he did not dream that that other was to
wield the divine might, nor that His perfect strength was to be
manifested in weakness, and to work its wonders by the might of
gentle, self-sacrificing love. But, though he dimly saw, he
perfectly adored. He felt himself unworthy (literally, insufficient)
to be the slave who untied (or, according to Matthew, 'bore') his
lord's sandals. How beautiful is the lowliness of that strong
nature! He stood erect in the face of priests and tetrarchs, and
furious women, and the headsman with his sword, but he lay prostrate
before his King.

Strength and royal authority were not all that he had to proclaim of
Messiah. 'He shall baptize you in the Holy Ghost and fire.' We
observe that the construction here is different from that in verse
16 ('with water'), inasmuch as the preposition 'in' is inserted,
which, though it is often used 'instrumentaly,' is here, therefore,
more probably to be taken as meaning simply 'in.' The two nouns are
coupled under one preposition, which suggests that they are fused
together in the speaker's mind as reality and symbol.