Ye know how through infirmity of the flesh I preached the gospel unto you at the first.
Galatians 4:13
"All the best translations have “because,” or its equivalent, in verse 13, instead of “through,” as in our ordinary version.
---What a flood of light upon Paul's labor among the Galatians we get from these few sentences!
---He was in great bodily affliction and physical pain when he first preached the Gospel in Galatia. 
Not only so, but that infirmity was the cause of his preaching the Gospel at that place. It is evident from his statement that he was obliged to stop in Galatia on account of physical infirmity, but instead of spending the time looking after his own comfort, he took advantage of the circumstance to preach the Gospel; and he evidently did it with the more vigor because of his infirmity. See 2 Cor. 11:23-30; 12:7-10.
What a marvel of the power of Christ in man that can use even his times of greatest physical weakness as an occasion for accomplishing the greatest work!
Here, also, we see another proof that
the Gospel does not depend upon man,
but on God.
It is not of the flesh,
but of the Spirit."
Sabbath School Lesson 1900