Matthew 4:23

When therefore He had caught them, then He begins in their presence to work miracles, by His deeds confirming the words of John concerning Him. And He was continually frequenting their synagogues, even by this instructing them that He was not a sort of adversary of God and deceiver, but that He was come in accordance with the Father. And while frequenting them, He did not preach only, but also showed forth miracles. And this, because on every occasion, whensoever anything is done strange and surprising, and any polity is introduced, God is wont to work miracles as pledges of His power, which He affords to them that are to receive His laws. Thus, for instance, when He was about to make man, He created a whole world, and then gave him that law which he had in Paradise. And when He was to give laws to Noah, He showed forth anew great miracles, in that He reduced again the whole creation to its elements, that fearful sea to prevail for a full year; and in that, amid so great a tempest, He preserved that righteous man. And in the time of Abraham too He vouchsafed many signs; as his victory in the war, the plague upon Pharaoh, his deliverance from dangers. And when about to legislate for the Jews, He showed forth those marvellous and great prodigies, and then gave the law. Just so in this case also, being to introduce a certain high polity, and to tell them what they had never heard, by the display of the miracles He confirms what He saith. Thus because the kingdom He was preaching appeared not, by the things that appear, He makes it, though invisible, manifest.

Kings, when about to go to war with their enemies, first gather an army, and so go out to battle; thus the Lord when about to war against the Devil, first collected Apostles, and then began to preach the Gospel. Because they being weak could not come to their physician, He as a zealous Physician went about to visit those who had any grievous sickness. The Lord went round the several regions, and after His example the pastors of each region ought to go round to study the several dispositions of their people, that for the remedy of each disease some medicine may be found in the Church. Or, He taught natural righteousness, those things which natural reason teaches, as chastity, humility, and the like, which all men of themselves see to be goods. Such things are necessary to be taught not so much for the sake of making them known as for stirring the heart. For beneath the prevalence of carnal delights the knowledge of natural righteousness sleeps forgotten. When then a teacher begins to denounce carnal sins, his teaching does not bring up a new knowledge, but recalls to memory one that had been forgotten. But He preached the Gospel, in telling of good things which the ancients had manifestly not heard of, as the happiness of heaven, the resurrection of the dead, and the like. Or, He taught by interpreting the prophecies concerning Himself; He preached by declaring the benefits that were to come from Himself. Or, by disease we may understand any passion of the mind, as avarice, lust, and such like, by malady unbelief, that is, weakness of faith. Or, the diseases are the more grievous pains of the body, the maladies the slighter. As He cured the bodily pains by virtue of His divine power, so He cured the spiritual by the word of His mercy. He first teaches, and then performs the cures, for two reasons. First, that what is needed most may come first; for it is the word of holy instruction, and not miracles, that edify the soul. Secondly, because teaching is commended by miracles, not the converse.

An example of life for doctors; that they should not be inactive, they are instructed in these words, And Jesus went about. That they should not be acceptors of persons the preachers are instructed in what follows, the whole of Galilee. That they should not go about empty, by the word teaching. That they should seek to benefit not few but many, in what follows, in their synagogues. That they should not preach error nor fable, but sound doctrine, is inculcated in the words, preaching the Gospel of the kingdom. 'Teaching' and 'preaching' differ; teaching refers to things present, preaching to things to come; He taught present commandments and preached future promises. That the teacher should study to commend his teaching by his own virtuous conduct is conveyed in those words, healing every sort of disease and malady among the people; maladies of the body, diseases of the soul.