Under the head of this preaching, in which he says Jesus engaged in all Galilee, we may also understand that discourse to be comprehended which was delivered on the mount, and which is detailed by Matthew. For the same Mark continues his account thus: "And there came a leper to Him, beseeching Him; and kneeling down to Him, said, If Thou wilt, Thou canst make me clean."  And he goes on with the rest of the story of the cleansing of this leper, in such a manner as to make it intelligible to us that the person in question is the very man who is mentioned by Matthew as having been healed at the time when the Lord came down from the mount after the delivery of His discourse. For this is how Matthew gives the history there: "Now, when He was come down from the mountain, great multitudes followed Him; and, behold, there came a leper, and worshipped Him, saying, Lord, if Thou wilt, Thou canst make me clean;"  and so on.
44. This leper is also referred to by Luke,  not indeed in this order, but after the manner in which the writers are accustomed to act, recording at a subsequent point things which have been omitted at a previous stage, or bringing in at an earlier point occurrences which took place at a later period, according as they had incidents suggested to their minds by the heavenly influence, with which indeed they had become acquainted before, but which they were afterwards prompted to commit to writing as they came up to their recollection. This same Luke, however, has also left us a version of his own of that copious discourse of the Lord, in a passage which he commences just as the section in Matthew begins. For in the latter the words run thus: "Blessed are the poor in spirit: for theirs is the kingdom of heaven;"  while in the former they are put thus: "Blessed be ye poor: for yours is the kingdom of God."  Then, too, much of what follows in Luke's narrative is similar to what we have in the other. And finally, the conclusion given to the sermon is repeated in both Gospels in its entire identity, -- namely, the story of the wise man who builds upon the rock, and the foolish man who builds upon the sand; the only difference being, that Luke speaks only of the stream beating against the house, and does not mention also the rain and the wind, as they occur in Matthew. Accordingly, it might very readily be believed that he has there introduced the self-same discourse of the Lord, but that at the same time he has omitted certain sentences which Matthew has inserted; that he has also brought in other sayings which Matthew has not mentioned; and that, in a similar manner, he has expressed certain of these utterances in somewhat different terms, but without detriment to the integrity of the truth.
45. This we might very well suppose to have been the case, as I have said, were it not that a difficulty is felt to attach to the circumstance that Matthew tells us how this discourse was delivered on a mount by the Lord in a sitting posture; while Luke says that it was spoken on a plain by the Lord in a standing posture. This difference, accordingly, makes it seem as if the former referred to one discourse, and the latter to another. And what should there be, indeed, to hinder [us from supposing] Christ to have repeated elsewhere some words which He had already spoken, or from doing a second time certain things which He had already done on some previous occasion? However, that these two discourses, of which the one is inserted by Matthew and the other by Luke, are not separated by a long space of time, is with much probability inferred from the fact that, at once in what precedes and in what follows them, both the evangelists have related certain incidents either similar or perfectly identical, so that it is not unreasonably felt that the narrations of the writers who introduce these things are occupied with the same localities and days. For Matthew's recital proceeds in the following terms: "And there followed Him great multitudes of people from Galilee, and from Decapolis, and from Jerusalem, and from Judæa, and from beyond Jordan. And seeing the multitudes, He went up into a mountain; and when He was set, His disciples came unto Him: and He opened His mouth, and taught them, saying, Blessed are the poor in spirit: for theirs is the kingdom of heaven;"  and so forth. Here it may appear that His desire was to free Himself from the great crowds of people, and that for this reason He went up into the mountain, as if He meant to withdraw Himself from the multitudes, and seek an opportunity of speaking with His disciples alone. And this seems to be certified also by Luke, whose account is to the following effect: "And it came to pass in those days, that He went out into a mountain to pray, and continued all night in prayer to God. And when it was day, He called unto Him His disciples: and of them He chose twelve, whom also He named apostles; Simon, whom He also named Peter, and Andrew his brother, James and John, Philip and Bartholomew, Matthew and Thomas, James the son of Alpheus, and Simon, who is called Zelotes, Judas the brother of James, and Judas Scarioth, which was the traitor. And He came down with them, and stood in the plain, and the company of His disciples, and a great multitude of people out of all Judæa and Jerusalem, and from the sea-coast of Tyre  and Sidon, which had come to hear Him, and to be healed of their diseases; and they that were vexed with unclean spirits were healed.  And the whole multitude sought to touch Him; for there went virtue out of Him, and healed them all. And He lifted up His eyes on His disciples, and said, Blessed be ye poor: for yours is the kingdom of heaven;"  and so on. Here the relation permits us to understand that, after selecting on the mountain twelve disciples out of the larger body, whom He also named apostles (which incident Matthew has omitted), He then delivered that discourse which Matthew has introduced, and which Luke has left unnoticed, -- that is to say, the one on the mount; and that thereafter, when He had now come down, He spoke in the plain a second discourse similar to the first, on which Matthew is silent, but which is detailed by Luke; and further, that both these sermons were concluded in the same manner. 
46. But, again, as regards what Matthew proceeds to state after the termination of that discourse -- namely this, "And it came to pass, when Jesus had ended these sayings, the people  were astonished at His doctrine,"  -- it may appear that the speakers there were those multitudes of disciples out of whom He had chosen the twelve. Moreover, when the evangelist goes on immediately in these terms, "And when He was come down from the mountain, great multitudes followed Him; and, behold, there came a leper and worshipped Him,"  we are at libertyto suppose that that incident took place subsequently to both discourses, -- not only after the one which Matthew records, but also after the one which Luke inserts. For it is not made apparent what length of time elapsed after the descent from the mountain. But Matthew's intention was simply to indicate the fact itself, that after that descent there were great multitudes of people with the Lord on the occasion when He cleansed the leper, and not to specify what period of time had intervened. And this supposition may all the more readily be entertained, since [we find that] Luke tells us how the same leper was cleansed at a time when the Lord was now in a certain city, -- a circumstance which Matthew has not cared to mention.
47. After all, however, this explanation may also be suggested, -- namely, that in the first instance the Lord, along with His disciples and no others, was on some more elevated portion of the mountain, and that during the period of His stay there He chose out of the number of His followers those twelve; that then He came down in company with them, not indeed from the mountain itself, but from that said altitude on the mountain, into the plain -- that is to say, into some level spot which was found on the slope of the mountain, and which was capable of accommodating great multitudes; and that thereafter, when He had seated Himself, His disciples took up their position next Him, and in these circumstances He delivered both to them and to the other multitudes who were present one discourse, which Matthew and Luke have both recorded, their modes of narrating it being indeed different, but the truth being given with equal fidelity by the two writers in all that concerns the facts and sayings which both of them have recounted. For we have already prefaced our inquiry with the position, which indeed ought of itself to have been obvious to all without the need of any one to give them counsel to that effect beforehand, that there is not [necessarily] any antagonism between writers, although one may omit something which another mentions; nor, again, although one states a fact in one way, and another in a different method, provided that the same truth is set forth in regard to the objects and sayings themselves. In this way, therefore, Matthew's sentence, "Now when He was come down from the mountain," may at the same time be understood to refer also to the plain, which there might very well have been on the slope of the mountain. And thereafter Matthew tells the story of the cleansing of the leper, which is also given in a similar manner by Mark and Luke.
 Mark 1:39.  Mark 1:40.  Matthew 8:1, 2.  Luke 5:12, 13. [It seems altogether more probable that the healing of the leper occurred, before the Sermon on the Mount, at the time indicated by Luke.--R.]  Matthew 5:3.  Luke 6:20.  Matthew 4:25, etc.  Various mss. and editions insert et before the Tyri = both of Tyre, although it is wanting in the Greek.  Qui vexabantur a spiritibus immundis curabantur.  Luke 6:12-20.  [The explanation suggested in 47 is altogether more probable.--R.]  Turbæ, multitudes.  Matthew 7:28.  Matthew 8:1, 2.
 Mark 1:40.
 Matthew 8:1, 2.
 Luke 5:12, 13. [It seems altogether more probable that the healing of the leper occurred, before the Sermon on the Mount, at the time indicated by Luke.--R.]
 Matthew 5:3.
 Luke 6:20.
 Matthew 4:25, etc.
 Various mss. and editions insert et before the Tyri = both of Tyre, although it is wanting in the Greek.
 Qui vexabantur a spiritibus immundis curabantur.
 Luke 6:12-20.
 [The explanation suggested in 47 is altogether more probable.--R.]
 Turbæ, multitudes.
 Matthew 7:28.
 Matthew 8:1, 2.