Adam Clarke's Commentary on the Bible

Verse 15 (Ephesians 5:15)

Walk circumspectly - Our word circumspect, from the Latin circirmspicio , signifies to look round about on all hands; to be every way watchful, wary, and cautious, in order to avoid danger, discern enemies before they come too nigh, and secure a man's interest by every possible and lawful means. But the original word ακριβως signifies correctly, accurately, consistently, or perfectly. Be ye, who have received the truth, careful of your conduct; walk by the rule which God has given you; do this as well in little as in great matters; exemplify your principles, which are holy and good, by a corresponding conduct; do not only profess, but live the Gospel. As you embrace all its promises, be careful also to embrace all its precepts; and behave yourselves so, that your enemies may never be able to say that ye are holy in your doctrines and profession, but irregular in your lives.

Not as fools, but as wise - Μη ὡς ασοφοι, αλλ ' ὡς σοφοι . The heathens affected to be called σοφοι , or wise men. Pythagoras was perhaps the first who corrected this vanity, by assuming the title of φιλοσοφος , a lover of wisdom; hence our term philosopher, used now in a much prouder sense than that in which the great Pythagoras wished it to be applied. The apostle here takes the term σοφος , and applies it to the Christian; and, instead of it, gives the empty Gentile philosopher the title of ασοφος , without wisdom, fool.

- Adam Clarke's Commentary on the Bible