Today's text from St John's Gospel, 7:1-30, chronicles the increasing tensions between Jesus and the Jewish authorities, such that he avoids precipitating a confrontation by telling his relatives that he is not going to Jerusalem for one of the three mandated major feasts (Tabernacles, or Sukkot). He then avoids notice by quietly slipping into Jerusalem at the last minute. When he does eventually emerge publicly, starts teaching, the debate becomes one over discernment of spirits: how to know when something said is true.
Here is the Latin (which can also be found over at New Advent; you can listen to it being read here (the Greek can be found here).
Post hæc autem ambulabat Jesus in Galilæam: non enim volebat in Judæam ambulare, quia quærebant eum Judæi interficere. 2 Erat autem in proximo dies festus Judæorum, Scenopegia. 3 Dixerunt autem ad eum fratres ejus: Transi hinc, et vade in Judæam, ut et discipuli tui videant opera tua, quæ facis. 4 Nemo quippe in occulto quid facit, et quærit ipse in palam esse: si hæc facis, manifesta teipsum mundo. 5 Neque enim fratres ejus credebant in eum. 6 Dicit ergo eis Jesus: Tempus meum nondum advenit: tempus autem vestrum semper est paratum. 7 Non potest mundus odisse vos: me autem odit, quia ego testimonium perhibeo de illo quod opera ejus mala sunt. 8 Vos ascendite ad diem festum hunc, ego autem non ascendo ad diem festum istum: quia meum tempus nondum impletum est. 9 Hæc cum dixisset, ipse mansit in Galilæa.10 Ut autem ascenderunt fratres ejus, tunc et ipse ascendit ad diem festum non manifeste, sed quasi in occulto. 11 Judæi ergo quærebant eum in die festo, et dicebant: Ubi est ille? 12 Et murmur multum erat in turba de eo. Quidam enim dicebant: Quia bonus est. Alii autem dicebant: Non, sed seducit turbas. 13 Nemo tamen palam loquebatur de illo propter metum Judæorum. 14 Jam autem die festo mediante, ascendit Jesus in templum, et docebat. 15 Et mirabantur Judæi, dicentes: Quomodo hic litteras scit, cum non didicerit? 16 Respondit eis Jesus, et dixit: Mea doctrina non est mea, sed ejus qui misit me. 17 Si quis voluerit voluntatem ejus facere, cognoscet de doctrina, utrum ex Deo sit, an ego a meipso loquar. 18 Qui a semetipso loquitur, gloriam propriam quærit; qui autem quærit gloriam ejus qui misit eum, hic verax est, et injustitia in illo non est. 19 Nonne Moyses dedit vobis legem: et nemo ex vobis facit legem? 20 Quid me quæritis interficere? Respondit turba, et dixit: Dæmonium habes: quis te quæret interficere? 21 Respondit Jesus et dixit eis: Unum opus feci, et omnes miramini: 22 propterea Moyses dedit vobis circumcisionem (non quia ex Moyse est, sed ex patribus), et in sabbato circumciditis hominem. 23 Si circumcisionem accipit homo in sabbato, ut non solvatur lex Moysi: mihi indignamini quia totum hominem sanum feci in sabbato? 24 Nolite judicare secundum faciem, sed justum judicium judicate.25 Dicebant ergo quidam ex Jerosolymis: Nonne hic est, quem quærunt interficere? 26 et ecce palam loquitur, et nihil ei dicunt. Numquid vere cognoverunt principes quia hic est Christus? 27 Sed hunc scimus unde sit: Christus autem cum venerit, nemo scit unde sit. 28 Clamabat ergo Jesus in templo docens, et dicens: Et me scitis, et unde sim scitis: et a meipso non veni, sed est verus qui misit me, quem vos nescitis. 29 Ego scio eum: quia ab ipso sum, et ipse me misit. 30 Quærebant ergo eum apprehendere: et nemo misit in illum manus, quia nondum venerat hora ejus.
And the English:
1] After these things Jesus walked in Galilee; for he would not walk in Judea, because the Jews sought to kill him.  Now the Jews' feast of tabernacles was at hand.  And his brethren said to him: Pass from hence, and go into Judea; that thy disciples also may see thy works which thou dost.  For there is no man that doth any thing in secret, and he himself seeketh to be known openly. If thou do these things, manifest thyself to the world.  For neither did his brethren believe in him. Then Jesus said to them: My time is not yet come; but your time is always ready.  The world cannot hate you; but me it hateth: because I give testimony of it, that the works thereof are evil.  Go you up to this festival day, but I go not up to this festival day: because my time is not accomplished.  When he had said these things, he himself stayed in Galilee.  But after his brethren were gone up, then he also went up to the feast, not openly, but, as it were, in secret.  The Jews therefore sought him on the festival day, and said: Where is he?  And there was much murmuring among the multitude concerning him. For some said: He is a good man. And others said: No, but he seduceth the people.  Yet no man spoke openly of him, for fear of the Jews.  Now about the midst of the feast, Jesus went up into the temple, and taught.  And the Jews wondered, saying: How doth this man know letters, having never learned? Jesus answered them, and said: My doctrine is not mine, but his that sent me.  If any man do the will of him; he shall know of the doctrine, whether it be of God, or whether I speak of myself.  He that speaketh of himself, seeketh his own glory: but he that seeketh the glory of him that sent him, he is true, and there is no injustice in him.  Did Moses not give you the law, and yet none of you keepeth the law?  Why seek you to kill me? The multitude answered, and said: Thou hast a devil; who seeketh to kill thee? Jesus answered, and said to them: One work I have done; and you all wonder:  Therefore, Moses gave you circumcision (not because it is of Moses, but of the fathers;) and on the sabbath day you circumcise a man.  If a man receive circumcision on the sabbath day, that the law of Moses may not be broken; are you angry at me because I have healed the whole man on the sabbath day?  Judge not according to the appearance, but judge just judgment.  Some therefore of Jerusalem said: Is not this he whom they seek to kill?  And behold, he speaketh openly, and they say nothing to him. Have the rulers known for a truth, that this is the Christ?  But we know this man, whence he is: but when the Christ cometh, no man knoweth whence he is.  Jesus therefore cried out in the temple, teaching, and saying: You both know me, and you know whence I am: and I am not come of myself; but he that sent me, is true, whom you know not.  I know him, because I am from him, and he hath sent me.  They sought therefore to apprehend him: and no man laid hands on him, because his hour was not yet come.
The texts St Thomas Aquinas selected for his Catena Aurea goes first to the issue of avoiding persecution:
AUG. As the believer in Christ would have in time to, come to hide himself from persecution, that no guilt might attach to such concealment, the Head began with doing Himself, what He sanctioned in the member; After these things Jesus walked in Galilee: for he would not walk in Jewry, because the Jews sought to kill Him...
THEOPHYL. He withdrew too now to Galilee, because the hour of His passion was not yet come; and He thought it useless to stay in the midst of His enemies, when the effect would only have been to irritate them the more. The time at which this happened is then given; Now the Jews; feast of tabernacles was at hand.
They also provide some background on the feast in question:
AUG. What the feast of tabernacles is, we read in the Scriptures. They used to make tents on the festival, like those in which they lived during their journey in the desert, after their departure from Egypt. They celebrated this feast in commemoration of the good things the Lord had done for them; though they were the very people who were about to slay the Lord. It is called the day of the feast, though it lasted many days.
CHRYS. It appears here, that a considerable time had passed since the last events. For when our Lord sat upon the mount, it was near the feast of the Passover and now it is the feast of tabernacles: so that in the five intermediate months the Evangelist has related nothing but the miracle of the loaves, and the conversation with those who ate of them. As our Lord was unceasingly working miracles, and holding disputes with people, the Evangelists could not relate all; but only aimed at giving those, in which complaint or opposition had followed on the part of the Jews as was as the case here.
Who are the 'brethren' referred to? Not literally Christ's siblings of course for he had none:
AUG. When you hear of our Lord's brethren, you must understand the kindred of Mary, not her offspring after our Lord's birth. For as the body of our Lord once only lay in the sepulcher, and neither before, nor after that once; so could not the womb of Mary have possibly conceived any other mortal offspring. Our Lord's works did not escape His disciples, but they escaped His brethren; hence their suggestion, That Your disciples may see the works that you do. They speak according to the wisdom of the flesh, to the Word that was made flesh, and add, For there is no man that does any thing in secret, and he himself seeks to be known openly. If you do these things, show Yourself to the world; as if to say, You do miracles, do them in the eyes of the world, that the world may honor You. Their admonitions aim at procuring glory for Him; and this very thing, viz. aiming at human glory, proved that they did not believe in Him, as we next read, For neither did His brethren believe in Him. They were Christ's kindred, hut they were on that very account above believing in Him.
These relatives seem to be operating from dubious motives:
CHRYS. It is striking to observe the great sincerity of the Evangelists; that they are not ashamed to mention things which appear to be to our Lord's disadvantage, but take particular care to tell us of them. It is a considerable reflection on our Lord, that His brethren do not believe on Him. The beginning of their speech has a friendly appearance about it: tent there is much bitterness in it, thus charging Him with the motives of fear and vain glory; No man, say they, does anything in secret: this was reproaching Him tacitly with fear; and was an insinuation too that His miracles had not been real and solid ones. In what follows, And he himself seeks to be known openly, they taunt Him with the love of glory. Christ however answers them mildly, teaching us not to take the advice of people ever so inferior to ourselves angrily; Then Jesus said to them, My time is not yet come: but your time is alway ready...
AUG. They gave Him advice to pursue glory, and not allow Himself to remain in concealment and obscurity; appealing altogether to worldly and secular motives. But our Lord was laying down another road to that very exaltation, viz. humility: My time, He says, i.e. the time of My glory, when I shall come to judge on high, is not yet come; but your time, i.e. the glory of the world, is always ready. And let us, who are the Lord's body, when insulted by the lovers of this world, say, Your time is ready: ours is not yet come. Our country is a lofty one, the way to it is low. Whoso rejects the way, why seek he the country?
CHRYS, Or there seems to be another meaning concealed in the words; perhaps they intended to betray Him to the Jews; and therefore He says, My time is not yet come, i.e. the time of My cross and death: but your time is always ready; for though you are always with the Jews, they will not kill you, because you are of the same mind with them: The world cannot hate you; but Me it hates, because I testify of it, that the works thereof are evil: as if He said, How can the world hate them who have the same wishes and aims with itself? It hates Me, because I reprove it. I seek not then glory from men; inasmuch as I hesitate not to reprove them, though I know that I am hated in consequence, and that My life is aimed at. Here we see that the hatred of the Jews was owing to His reproofs, not to His breaking the sabbath.
The central verses of the text are surely those dealing with the tests of discernment: the person teaching must be acting not to seek secular adulation, but rather to achieve the real objective; and the person hearing must be properly disposed:
AUG. Should any one however not understand this, let him hear the advice which immediately follows from our Lord: If any man will do His will, he shall know of the doctrine, whether it be of God, or whether I speak of Myself. What means this, If any man will do His will? To do His will is to believe in Him, as He Himself says, This is the work of God, that you believe in Him whom He has sent. And who does not know, that to work the work of God, is to do His will? To know is to understand. Do not then seek to understand in order to believe, but believe in order to understand, for, Except you believe, you shall not understand.
CHRYS. This is as much as to say, Put away the anger, envy, and hatred which you have towards Me, and there will be nothing to prevent your knowing, that the words which I speak are from God. Then He brings in an irresistible argument taken from human experience: He that speaks of himself, seeks his own glory: as if to say, He who aims at establishing some doctrine of his own, does so for no purpose, but to get glory. But I seek the glory of Him that sent me, and wish to teach you for His, i.e. another's, sake: and then it follows, But he that seeks His glory that sent Him, the same is true, and there is no unrighteousness in Him.
THEOPHYL. As if He said, I speak the truth, because My doctrine contains the truth there is no unrighteousness in Me, because I usurp not another's glory.
AUG. He who seeks his own glory is Antichrist. But our Lord set us an example of humility, in that being found in fashion as a man, He sought His Father's glory, not His own. You, when you do good, take glory to yourself, when you do evil, upbraid God.
CHRYS. Observe, the reason why He spoke so humbly of Himself, is to let men know, that He does not aim at glory, or power; and to accommodate Himself to their weakness, and to teach them moderation, and a humble, as distinguished from an assuming, way of speaking of themselves.