Ephesians 4:17

(17) This I say therefore.—The phrase “This I say” seems to be used by St. Paul in returning (so to speak) from some lofty aspiration or profound reasoning, in which some might not be able to follow him, to a solid, practical ground, which all may tread. (See, for example, 1 Corinthians 15:50.) Here he is not content to use this phrase simply, but he enforces it by the solemnity of the adjuration “I testify” (comp. Acts 20:26; Galatians 5:3), which properly means, “I call God to witness the truth of what I say”—a phrase found in express terms in Romans 1:9; 2 Corinthians 1:23; Philippians 1:8; 1 Thessalonians 2:5. Nor was even this enough, for he adds “in the Lord”—that is, in the name, authority, and spirit of the Lord Jesus Christ Himself. The whole form is therefore one of peculiar force and solemnity.

The vanity of their mind.—In these words St. Paul describes the fundamental condition of heathenism. The “mind,” that is (as in Romans 7:23; Romans 7:25), the “inner man”—the spiritual intuition of invisible principles of truth and right, which is the true humanity—has become “subject to vanity” (Romans 8:20),—the vanity of which the Book of Ecclesiastes so often speaks. In losing the living conception of a living God, it has lost also the conception of the true object and perfection of human life; and so wanders on aimless, hopeless, reckless, as in a dream. With what absolute fidelity St. Paul describes the heathen world of his day, its history and its literature alike testify. Compare with the whole passage the picture drawn in Romans 1:21-32, “They became vain in their imaginations, and their foolish heart was darkened,” &c. The difference is that in the latter passage the prominent idea is mainly of “judicial blindness,” sent by God as a penalty on wilful apostasy from Him, whereas here St. Paul rather dwells on self-chosen blindness and hardness of heart.