(30) What dost thou work?--They feel that His words are an assertion that He is the Messiah, and they demand of Him Messianic signs and works. Do they demand a sign who had seen the thousands fed, and would then have made Him a king? It was but yesterday that He was obliged to withdraw from the enthusiasm of the multitude. Do they today need a further proof? The answer is to be found partly in the fact that a feeling soon quickened is soon cooled, and that even the disciples had not learnt the true meaning of the earlier sign (John 6:19); and partly in the fact that He Himself had taught them since, that the work of life was spiritual and eternal, and that He too could give them that food. This seems to them a claim to a power in the world of spirit analogous to that which He had exercised in the world of matter. They demand proof of this power. Where is the sign of it? What is the work that He Himself does answering to the work of faith which He demands from them?

Verse 30. - They said therefore to him, What then doest thou as a sign that we may see and believe thee? There is a kind of irony in the inquiry, "What doest thou?" There is at least some ironical mystification of the words of Jesus, "If we have not seen, as thou sayest, the sign, which we thought sufficient to induce us to hail thee as our Prophet-King, what sign wilt thou give us now? If we are to believe on thee, what sign art thou ready to show now that we may see it, and believe thee, i.e. take thy word as trustworthy, and so begin to consider whether it will be safe to believe in, to entrust ourselves to, thee?" It has been the peculiarity of the Jewish mind in all ages to seek after a sign, to desire some irresistible reason for invincible faith. In certain stages of immaturity and states of unrest we passionately ask for signs even now - for something more than silent words, for more than past memories, for some voice out of heaven, some gleams of glory, that "we may see and believe." These frames of mind are no whit more reprehensible than the Greek demand for unanswerable argument, for logical harmony, or for sure demonstration. They said to him, What dost thou work? How wilt thou vindicate thy demand for such implicit trust? This very question has been made into a reason for breaking all historic connection between the miracle of the feeding and the dialogue and discourse before us (Grotius, Kuinoel, B. Bauer, Weisse, and Schenkel). It is, however, clear that they were still revolving the work of the past day, which Jesus had depreciated per se, and which, apart from the higher lesson it might have conveyed to them, and apart from the wrong conclusion they had been drawing from it, grievously perplexed them, and seemed insufficient to establish the new claim of Jesus. They, too, begin to depreciate it in comparison with a corresponding sign which Moses had wrought for their fathers. Verily if Moses had been the mediator of the portentous sign of the manna, if Moses had been its real anther, it was a much greater sign than what they witnessed at Bethsaida. For forty years the miraculous bread had been lavished upon them. Daily and weekly it proved its supernatural character. In quantity, quality, prolongation, and renewal day by day, and in its cessation when they ate the fresh corn of Canaan, they not unnaturally saw something immeasurably more vast and imposing than the offer of a single meal to a little company of five thousand men. Christ had wrought a τέρας, an ἔργον, but they had not seen the real σημεῖον involved in it. He himself suggested that something entirely different from that meal, and different from their conclusions concerning it was the true "sign." Let him work the same adequate sign. They are not repudiating all knowledge of the feeding of the five thousand, nor revealing their ignorance of it. They are thrown back on their ingrained passion for supernatural proof, not as yet satisfied by what Christ had done.

6:28-35 Constant exercise of faith in Christ, is the most important and difficult part of the obedience required from us, as sinners seeking salvation. When by his grace we are enabled to live a life of faith in the Son of God, holy tempers follow, and acceptable services may be done. God, even his Father, who gave their fathers that food from heaven to support their natural lives, now gave them the true Bread for the salvation of their souls. Coming to Jesus, and believing on him, signify the same. Christ shows that he is the true Bread; he is to the soul what bread is to the body, nourishes and supports the spiritual life. He is the Bread of God. Bread which the Father gives, which he has made to be the food of our souls. Bread nourishes only by the powers of a living body; but Christ is himself living Bread, and nourishes by his own power. The doctrine of Christ crucified is now as strengthening and comforting to a believer as ever it was. He is the Bread which came down from heaven. It denotes the Divinity of Christ's person and his authority; also, the Divine origin of all the good which flows to us through him. May we with understanding and earnestness say, Lord, evermore give us this Bread.They said therefore unto him,.... Seeing he proposed believing in him as the grand work of God to be done, and what is most acceptable in his sight:

what sign showest thou then, that we may see and believe thee? The people of the Jews were always requiring signs and wonders, and when they had one and another shown them, they still sought for more, and were never satisfied; see Matthew 12:39. These men had lately seen various signs and miracles of Christ, as healing the sick, and feeding live thousand of them, and more, with five loaves, and two fishes; and though, for the time present, these had some influence upon them, and they were ready to believe he was that prophet; yet now, at least some of them, begin to retract, and signify, that unless some other, and greater signs were shown, they should not believe in him as the Messiah:

what dost thou work? more than others, or Moses. They seem to make light of the miracle of the loaves, or at least require some greater sign and miracle, to engage their belief in him as the Messiah; and as they were lovers of their bellies, and expected dainties in the times of the Messiah, they seem to move for, and desire miracles of that kind to be wrought; and which sense the following words confirm.