36 But when he saw the multitudes, he was moved with compassion on them, because they fainted, and were scattered abroad, as sheep having no shepherd.
[AD 367] Hilary of Poitiers on Matthew 9:36
No instigator had stirred up the crowds. They were not harassed and helpless because of some mishap or disturbance. So why is Jesus so moved with compassion for these people? Clearly the Lord has pity on these people held in the sway of an unclean spirit and burdened by the law, because no shepherd was about to restore to them the guardianship of the Holy Spirit. The fruit of this gift was indeed potentially abundant but not yet harvested by anyone. The bounty of the Spirit overwhelms the multitude of those who take hold of it. For no matter how much it is gathered by everyone, it abounds in fruitfulness. And because it is good to have many people through whom he is served, he orders his disciples to pray to the Lord of the harvest to send forth as many laborers as possible into the harvest. He prays that God may bestow an abundance of reapers to take hold of what the gift of the Holy Spirit was preparing. Through prayer and exhortation, God pours out this gift upon us.

[AD 367] Hilary of Poitiers on Matthew 9:36-38
Figuratively; When salvation was given to the Gentiles, then all cities and towns were enlightened by the power and entrance of Christ, and escaped every former sickness and infirmity. The Lord pities the people troubled with the violence of the unclean Spirit, and sick under the burden of the Law, and having no shepherd at hand to bestow on them the guardianship of the Holy Spirit. But of that gift there was a most abundant fruit, whose plenty far exceeded the multitude of those that drank thereof; how many soever take of it, yet an inexhaustible supply remains; and because it is profitable that there should be many to minister it, He bids us ask the Lord of the harvest, that God would provide a supply of reapers for the ministration of that gift of the Holy Spirit which was made ready; for by prayer this gift is poured out upon us from God.

[AD 407] John Chrysostom on Matthew 9:36
See again His freedom from vainglory. That He may not draw all men unto Himself, He sends out His disciples.

And not with this view only, but that He might also teach them, after practising in Palestine, as in a sort of training-school, to strip themselves for their conflicts with the world. For this purpose then He makes the exercises even more serious than the actual conflicts, so far as pertained to their own virtue; that they might more easily engage in the struggles that were to ensue; as it were a sort of tender nestlings whom He was at length leading out to fly. And for the present He makes them physicians of bodies, dispensing to them afterwards the cure of the soul, which is the principal thing.

And mark how He points out the facility and necessity of the thing. For what says He? The harvest truly is plenteous, but the laborers are few. That is, not to the sowing, says He, but to the reaping do I send you. Which in John He expressed by, Other men labored, and you are entered into their labors. John 4:38

And these things he said, at once repressing their pride, and preparing them to be of good courage, and signifying that the greater part of the labor came first.

And contemplate Him here too beginning from love to man, not with any requital. For He had compassion, because they were troubled and scattered abroad as sheep having no shepherd. This is His charge against the rulers of the Jews, that being shepherds they acted the part of wolves. For so far from amending the multitude, they even marred their progress. For instance, when they were marvelling and saying, It was never so seen in Israel: these were affirming the contrary, He casts out devils through the prince of the devils.
[AD 407] John Chrysostom on Matthew 9:36-38
The Lord would refute by actions the charge of the Pharisees, who said, He casteth out dæmons by the Prince of the dæmons; for a dæmon having suffered rebuke, does not return good but evil to those who have not shown him honour. But the Lord on the other hand, when He has suffered blasphemy and contumely, not only does not punish, but does not utter a hard speech, yea He shows kindness to them that did it, as it here follows, And Jesus went about all their towns and villages. Herein He teaches us not to return accusations to them that accuse us, but kindness. For he that ceases to do good because of accusation, shows that his good has been done because of men. But if for God's sake you do good to your fellow-servants, you will not cease from doing good whatever they do, that your reward may be greater.

Nor does Christ's goodness rest here, but He manifests His care for them, opening the bowels of His mercy towards them; whence it follows, And seeing the multitudes, he had compassion upon them.

This is an accusation against the rulers of the Jews, that being shepherds they appeared like wolves; not only not improving the multitude, but hindering their progress. For when the multitude marvelled and said, It was never so seen in Israel, these opposed themselves, saying, He casteth out dæmons by the prince of the dæmons. (vid. Ps. 102:19.)

He privately insinuates Himself to be the Lord; for it is He Himself who is Lord of the harvest. For if He sent the Apostles to reap what they had not sown, it is manifest that He sent them not to reap the things of others, but what He had sown by the Prophets. But since the twelve Apostles are the labourers, He said, Pray ye the Lord of the harvest, that he would send labourers into his harvest; and notwithstanding He added none to their number, but rather He multiplied those twelve many times, not by increasing their numbers, but by giving them more abundant grace.

He shows us that it is a great gift that one should have the power of rightly preaching, in that He tells them that they ought to pray for it. Also we are here reminded of the words of John concerning the threshing-floor, and the fan, the chaff, and the wheat.

[AD 420] Jerome on Matthew 9:36
(Verse 36.) But seeing the crowds, he had compassion on them, because they were harassed and helpless, like sheep without a shepherd. Then he said to his disciples. The persecution of the flock and sheep and the disturbance of the crowds is the fault of the shepherds and the vice of the leaders. Hence it follows.

[AD 420] Jerome on Matthew 9:36-38
Observe how equally in villages, cities, and towns, that is to great as well as small, He preaches the Gospel, not respecting the might of the noble, but the salvation of those that believe. It follows, Teaching in their synagogues; this was His meat, going about to do the will of His Father, and saving by His teaching such as yet believed not.

He first preached and taught, and then proceeded to heal sicknesses, that the works might convince those who would not believe the words. Hence it follows, Healing every sickness and every disease, for to Him alone nothing is impossible.

The great harvest denotes the multitude of the people; the few labourers, the want of instructors.

[AD 430] Augustine of Hippo on Matthew 9:36-38
(De Cons. Ev. ii. 29.) This account of the two blind men and the dumb dæmon is read in Matthew only. The two blind men of whom the others speak are not the same as these, though something similar was done with them. So that even if Matthew had not also recorded their cure, we might have seen that this present narrative was of a different transaction. And this we ought diligently to remember, that many actions of our Lord are very much like one another, but are proved not to be the same action, by being both related at different times by the same Evangelist. So that when we find cases in which one is recorded by one Evangelist, and another by another, and some difference which we cannot reconcile between their accounts, we should suppose that they are like, but not the same, events.

[AD 533] Remigius of Rheims on Matthew 9:36-38
Understand, 'of God;' for though temporal blessings are also proclaimed, yet they are not called The Gospel. Hence the Law was not called a Gospel, because to such as kept it, it held out not heavenly, but earthly, goods.

It should be known that those whom He healed outwardly in their bodies, He also healed inwardly in their souls. Others cannot do this of their own power, but can by God's grace.

Herein Christ shows in Himself the disposition of the good shepherd and not that of the hireling. Why He pitied them is added, Because they were troubled, and sick as sheep that have no shepherd—troubled either by dæmons, or by divers sicknesses and infirmities.

But when the Son of God looked down from heaven upon the earth, to hear the groans of the captives, straight a great harvest began to ripen; for the multitude of the human race would never have come near to the faith, had not the Author of human salvation looked down from heaven; and it follows, Then said he unto his disciples, The harvest truly is great, but the labourers are few.

For the number of the Apostles was small in comparison of so great crops to be reaped. The Lord exhorts His preachers, that is, the Apostles and their followers, that they should daily desire an increase of their number; Pray ye therefore the Lord of the harvest, that he would send forth labourers into his harvest.

Or, He then increased their number when He chose the seventy and two, and then when many preachers were made what time the Holy Spirit descended upon the believers.

[AD 1107] Theophylact of Ohrid on Matthew 9:36
. They did not have a shepherd. For their rulers not only failed to correct them, but even harmed them. The mark of the true shepherd is to have compassion for his flock.
[AD 1274] Glossa Ordinaria on Matthew 9:36-38
(non occ.) He taught in their synagogues the Gospel of the Kingdom, as it follows, Preaching the Gospel of the Kingdom.

(ap. Anselm.) By disease we may understand complaints of long standing, by sickness any lesser infirmity.

(ap. Anselm.) Or, troubled by dæmons, and sick, that is, benumbed and unable to rise; and though they had shepherds, yet they were as though they had them not.

(ap. Anselm.) The harvest are those men who can be reaped by the preachers, and separated from the number of the damned, as grain is beaten out from the chaff that it may be laid up in granaries.