Adam Clarke's Commentary on the Bible

Verse 17 (Ephesians 5:17)

Wherefore be ye not unwise - Μη γινεσθε αφρονες· Do not become madmen. Here is a most evident allusion to the orgies of Bacchus, in which his votaries acted like madmen; running about, tossing their heads from shoulder to shoulder, appearing to be in every sense completely frantic. See the whole of the passage in Livy, to which I have referred on Ephesians 5:12 .

But understanding what the will of the Lord is - It is the will of God that ye should be sober, chaste, holy, and pure. Get a thorough understanding of this; acquaint yourselves with God's will, that ye may know how to glorify him.

- Adam Clarke's Commentary on the Bible