Ye know that, through infirmity of the flesh. He recalls to their recollection the friendly and respectful manner in which they had received him, and he does so for two reasons. First, to let them know that he loved them, and thus to gain a ready ear to all that he says; and secondly, to encourage them, that, as they had begun well, they would go on in the same course. This mention of past occurrences, then, while it is an expression of his kind regards, is intended likewise as an exhortation to act in the same manner as they had done at an earlier period. By infirmity of the flesh he means here, as in other places, what had a tendency to make him appear mean and despised. Flesh denotes his outward appearance, which the word infirmity describes to have been contemptible. Such was Paul when he came among them, without show, without pretense, without worldly honors or rank, without everything that could gain him respect or estimation in the eyes of men. Yet all this did not prevent the Galatians from giving him the most honorable reception. The narrative contributes powerfully to his argument, for what was there in Paul to awaken their esteem or veneration, but the power of the Holy Spirit alone? Under what pretext, then, will they now begin to despise that power? Next, they are charged with inconsistency, since no subsequent occurrence in the life of Paul could entitle them to esteem him less than before. But this he leaves to be considered by the Galatians, contenting himself with indirectly suggesting it as a subject of consideration.

Ye know how - To show them the folly of their embracing the new views which they had adopted, he reminds them of past times, and particularly of the strength of the attachment which they had evinced for him in former days.
Through infirmity of the flesh - Greek "Weakness" (ἀσθένειαν astheneian); compare the 1-Corinthians 2:3 note; 2-Corinthians 10:10; 2-Corinthians 12:7 notes.

Ye know how through infirmity - The apostle seems to say that he was much afflicted in body when he first preached the Gospel to them. And is this any strange thing, that a minister, so laborious as St. Paul was, should be sometimes overdone and overcome by the severity of his labors? Surely not. This might have been only an occasional affliction, while laboring in that part of Asia Minor; and not a continual and incurable infirmity, as some have too hastily conjectured.

Ye know how through (m) infirmity of the flesh I preached the gospel unto you at the first.
(m) Many afflictions.

Ye know how, through infirmity of the flesh,.... Meaning either their infirmity, to which the apostle accommodated himself in preaching the Gospel to them, delivering it in such a manner as suited with their capacities, feeding them with milk, and not with strong meat; or his own infirmity, respecting either some particular bodily infirmity and disorder, as the headache, with which he is said to be greatly troubled; or the weakness of his bodily presence, the mean outward appearance he made, the contemptibleness of his voice, and the great humility with which he behaved; or rather the many reproaches, afflictions, and persecutions which attended him, when, says he,
I preached the Gospel unto you at the first; not the law, but the Gospel; and this he did at his first entrance among them, and was the first that preached it to them, and was the means of their conversion; and therefore, being their spiritual Father, they ought to be as he was, and follow him as they had him for an example.

how through infirmity--rather, as Greek, "Ye know that because of an infirmity of my flesh I preached," &c. He implies that bodily sickness, having detained him among them, contrary to his original intentions, was the occasion of his preaching the Gospel to them.
at the first--literally, "at the former time"; implying that at the time of writing he had been twice in Galatia. See my Introduction; also see on Galatians 4:16, and Galatians 5:21. His sickness was probably the same as recurred more violently afterward, "the thorn in the flesh" (2-Corinthians 12:7), which also was overruled to good (2-Corinthians 12:9-10), as the "infirmity of the flesh" here.

I preached to you, notwithstanding infirmity of the flesh - That is, notwithstanding bodily weakness, and under great disadvantage from the despicableness of my outward appearance.