Corpus Scriptorum Ecclesiasticorum Latinorum, Vol. LVI: Augustini Epistulae Pars III

...fast frequently, but your disciples do not fast? And to John: Master, to whom you bore witness beside the Jordan, behold his disciples are baptizing, and many are coming to him. By this statement, they signify the envy arising from the magnitude of the signs and the bitterness of jealousy, asking why He, though baptized by John, dares to baptize Himself, and why a much larger crowd flocks to Him than had previously come to John. And lest perhaps the people, not knowing, might think that John was being disparaged by this statement, He concludes with praises of him and began to say of John to the crowds standing around: What did you go out to the desert to see? A reed shaken by the wind? And what did you go out into the solitude to see? A man clothed in soft garments? and the rest.

The sense of this statement is: Did you go out into the desert to see a man like a reed, swayed in various directions by the breath of the winds? So that he whom He had praised before, he might now doubt; and he of whom he had previously said: Behold the Lamb of God, might now ask whether it is He or another who has come or is to come? And because every false preaching chases profit and seeks human glory, so that gains may be born through glory, He asserts that he who is clothed in camel’s hair cannot succumb to any flattery, and that he who feeds on locusts and wild honey does not seek wealth, and that his rigid and austere life avoids the halls of palaces, which are sought by those who are clothed in fine linen and silk and soft things. And He calls him not only a prophet, who is accustomed to predict future things, but more than a prophet, because he pointed out that He has arrived whom they said would come, saying: Behold the Lamb of God.