14 Now about the midst of the feast Jesus went up into the temple, and taught.

[The midst of the feast] Jesus had arrived at the feast quietly, but part way through the week he chose to reveal himself and begin teaching.

15 And the Jews marvelled, saying, How knoweth this man letters, having never learned?

[How knoweth this man letters, having never learned?] Jewish education emphasized the knowledge of their own scriptures and the traditions of their elders. In this learning our blessed Lord excelled. No person ever spoke with more authority or knew how to make more proper use and better application of Jewish allegories and parables because none had ever understood the Scriptures as he did. No one ever cited them more successfully or ever showed their accomplishments in so complete and satisfactory a manner. Because these branches of learning were taught at the Jewish schools, and our Lord had never attended there, they were astonished to find him excelling in that sort of learning, of which they themselves professed to be the sole teachers.

16 Jesus answered them, and said, My doctrine is not mine, but his that sent me.

[My doctrine is not mine] Jesus speaks these words to draw the attention of the Jews from the teaching of man to the teaching of God; and to show that he was the promised Messiah, the very person on whom, according to the prophet, Isaiah 11:2, the Spirit of Jehovah - the Spirit of wisdom, counsel, understanding, might and knowledge should rest.

17 If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.

[Whether it be of God, or whether I speak of myself] I will give you a sure rule by which you may judge my doctrine: If you really wish to do the will of God, begin the practice of it; then take my doctrine, and apply it to all that you know of what God requires of man. If you find one of my teachings to be contrary to the nature, perfection and glory of God, or contrary to the present or eternal welfare of men, then you shall be at liberty to assert that my doctrine is human and erroneous, and God has not sent me. But if, on the contrary, ye find that the sum and substance of my preaching is, That men shall love God with all their heart, soul, mind and strength, and their neighbor as themselves, and that this doctrine brings glory to God in the highest while it produces peace and good will among men; then acknowledge that God has visited you, and receive me as the Messiah promised to your fathers.

18 He that speaketh of himself seeketh his own glory: but he that seeketh his glory that sent him, the same is true, and no unrighteousness is in him.

[He that speaketh of himself] I will give you another rule whereby you may know whether or not I am from God: If I speak to promote my own glory, to gratify my vanity, or to secure and promote my secular interests, then reject me as a deceiver and false prophet. But if I act only to promote the glory of God and to induce all men to love and obey him, then you cannot help but acknowledge me at least as a true prophet. And if you add this to the proofs which I have given of my mission and power, you must acknowledge me as the mighty power of God and the promised Messiah.

[And no unrighteousness is in him] Or, a more literal translation, There is no falsehood in him.

19 Did not Moses give you the law, and yet none of you keepeth the law? Why go ye about to kill me?

[Did not Moses give you the law] The scribes and Parisees denounced our Lord to the multitude as a deceiver; and they based their accusations on this, that he was not an exact observer of the law, for he had healed a man on the Sabbath day (John 5:9-10) so consequently must be a false prophet. They insinuated that the interests of religion required him to be put to death: (1) as a violator of the law, and, (2) as a false prophet and deceiver of the people.

20 The people answered and said, Thou hast a devil: who goeth about to kill thee?

[Who goeth about to kill thee?] You must be demon posessed. You are imagining things. No one desires to put you to death. It is not difficult to imagine that some of the voices raised in the crowd were planted there by Jesus' enemies to initiate distrust. Verse 13 tells us that the crowd knew enough to not speak openly of him for fear of the Jews.

21 Jesus answered and said unto them, I have done one work, and ye all marvel.

[I have done one work] That of curing the impotent man on the Sabbath during a prior visit to Jerusalem. Please review John 5:1-18.

22 Moses therefore gave unto you circumcision; (not because it is of Moses, but of the fathers;) and ye on the sabbath day circumcise a man.
23 If a man on the sabbath day receive circumcision, that the law of Moses should not be broken; are ye angry at me, because I have made a man every whit whole on the sabbath day?

[Not because it is of Moses] Circumcision was not initiated by the Mosaic law, but was given first to Abraham and continued among his posterity until the giving of the law. See Genesis 17:9-14 and Leviticus 12;3.

[Ye...circumcise a man] That is, a male child; for every male child was circumcised when eight days old; and if the eighth day after his birth happened to be a sabbath he was nevertheless circumcised, that the law might not be broken. From this and several other circumstances it is evident that the keeping of the sabbath, even in the strictest sense of the word, did not forbid works of necessity and mercy to be done on it. If the Jews had said, "Why did you not defer the healing of the sick man until the ensuing day?" Jesus might well have answered, "Why do ye not defer the circumcising of your children to the ensuing day when the eighth day happens to be a sabbath?"

[Every whit whole] The law of circumcision required the removal of a small portion of flesh, which was considered a blot and reproach among the Hebrews, because it made them similar to the nations who were not in the covenant with God. Christ, to this, opposes the complete cure of the infirm man who was diseased throughout his whole body. If one was permitted on the Sabbath day, surely the other had a stronger reason to recommend it.

24 Judge not according to the appearance, but judge righteous judgment.

[Judge righteous judgement] Attend to the law, not merely in the letter, but in its spirit and design.

25 Then said some of them of Jerusalem, Is not this he, whom they seek to kill?
26 But, lo, he speaketh boldly, and they say nothing unto him. Do the rulers know indeed that this is the very Christ?

[That this is the very Christ?] Calmet observes that there were three classes in the multitude which was hearing our Lord teach. (1) The rulers, priests and Pharisees, declared enemies of Christ. (2) The inhabitants of Jerusalem, who knew the sentiments of their rulers concerning him. (3) The strangers who, from different regions, had come up to Jerusalem to the feast, and who heard Christ attentively, being ignorant of the designs of the rulers against him. The question in the minds of the Jerusalem Jews was that perhaps the rulers had become convinced that this was the Christ and had dropped their opposition to him.

27 Howbeit we know this man whence he is: but when Christ cometh, no man knoweth whence he is.

[No man knoweth whence he is] It was well known that Messiah was to be born in Bethlehem, in the city of the family of David (Verse 42) but from Isaiah 53:8, Who shall declare his generation? they probably thought that there would be something so peculiarly mysterious about the birth or in the manner of his appearing that no person could fully understand. Had they known of his miraculous conception they would have been relieved on that point.

28 Then cried Jesus in the temple as he taught, saying, Ye both know me, and ye know whence I am: and I am not come of myself, but he that sent me is true, whom ye know not.

[Ye both know me, and ye know whence I am] Jesus knew the hearts and minds of his listeners. While some did not wish to acknowledge it, their innermost being was responding to his words. I am no self-created or self-authorized prophet; I came from God: -- the testimony of John the Baptist, the descent of the Holy Ghost, the voice from heaven, the purity and excellence of my doctrine and the multitude of my miracles sufficiently attest to this. Now God is true who has born testimony to me, but you know him not, therefore you disregard his testimony. A straightforward slap in the face of the religious leadership present that day.

29 But I know him: for I am from him, and he hath sent me.

[But I know him] You may not know him, but I do. I am from God. He has sent me. Whether or not you accept me does not alter the truth.

30 Then they sought to take him: but no man laid hands on him, because his hour was not yet come.

[They sought to take him] When one is being exposed as a fraud, supposedly representing God but not really in touch with him, there are many ways in which that one may respond. Attempting to silence the exposer was the response of the day.
God's plan was for Jesus to die on the cross for the sins of the world. This situation was not out of control but proceedng according to plan. God had to harden Pharoh's heart to make him behave according to plan. Did the Jewish leadership require such assistance? (Search for hardened.)

31 And many of the people believed on him, and said, When Christ cometh, will he do more miracles than these which this man hath done?

Will he do more miracles] It was the belief of the Jews that, when Messiah came, he would do many miracles.In order that they might have the fullest proof of the Divine mission of Christ, it had pleased God to have all miracles cease for between four and five hundred years. John the Baptist himself had not wrought any. Jesus miracles therefore were a full proof of his Divine mission.

32 The Pharisees heard that the people murmured such things concerning him; and the Pharisees and the chief priests sent officers to take him.

The people began to be convinced that he was the Messiah; and as they began whispering this among themselves, the Parisees and others thought that it was high time to put him to death. Compare the Jewish religious leaders' attitude toward the Messiah with that of King Herod some thirty years earlier, shortly after the birth of Christ. Matthew chapter 2