2 “When the evening had come, they brought unto Him many that were possessed with devils: and He cast out the spirits from them with a word, and healed all that were sick: that it might be fulfilled which was spoken by the Prophet Esaias, that He took our infirmities, and bare our sicknesses.”
Do you see the multitude, by this time growing in faith? For not even when the time pressed could they endure to depart, nor did they account it unseasonable to bring their sick to Him at eventide.
But mark, I pray you, how great a multitude of persons healed the evangelists pass quickly over, not mentioning one by one, and giving us an account of them, but in one word traversing an unspeakable sea of miracles. Then lest the greatness of the wonder should drive us again to unbelief, that even so great a people and their various diseases should be delivered and healed by Him in one moment of time, He brings in the prophet also to bear witness to what is going on: indicating the abundance of the proof we have, in every case, out of the Scriptures; such, that from the miracles themselves we have no more; and He says, that Esaias also spoke of these things; “He took our infirmities, and bare our sicknesses.” He said not, “He did them away,” but “He took and bare them;” which seems to me to be spoken rather of sins, by the prophet, in harmony with John, where he says, “Behold the Lamb of God, that bears the sin of the world.”
How then does the evangelist here apply it to diseases? Either as rehearsing the passage in the historical sense, or to show that most of our diseases arise from sins of the soul. For if the sum of all, death itself, has its root and foundation from sin, much more the majority of our diseases also: since our very capability of suffering did itself originate there.
Source: Homilies on the Gospel of St. Matthew (New Advent)