Adam Clarke on Philippians 4:12

I know - how to be abased - I have passed through all these states; I know how to conduct myself in each, and how to extract good from all. And he had passed through these things, especially the hardships, so that he had learned the lesson perfectly, as the word μεμυημαι implies; he was thoroughly instructed; fully initiated into all the mysteries of poverty and want, and of the supporting hand of God in the whole. See here the state to which God permitted his chief apostle to be reduced! And see how powerfully the grace of Christ supported him under the whole! How few of those who are called Christian ministers or Christian men have learned this important lesson! When want or affliction comes, their complaints are loud and frequent; and they are soon at the end of their patience.