Romans 1:14

I am debtor i.e. "I owe it to them to impart to them the Gospel." See 1 Corinthians 9:16-17; where St Paul speaks as a "dispenser" or "steward" of the Gospel, who is absolutely bound ("it is laid on me") to give the "portion of food in due season" to those whom he can reach.

the Greeks, and to the Barbarians A familiar division of mankind. Barbarusoriginally meant "a speaker of an unintelligible tongue;" then, in Greek, the speaker of a language not Greek. Thus the Romans were as much barbarias the Scythians; and indeed in the older Latin writers we find the word used by themselves, with reference to their own language, as a sort of synonym for "non-Greek." But when Rome more and more added culture to power the word was practically restricted to nations other than Greek and Latin, and so probably here. The word "Greeks" (Hellenes), in such contrasts as this, had come, by St Paul's time, to include Romans. Every educated Roman was trained in Greek speech and literature. Some of the "Roman" Christians were no doubt true Hellenes, and, as a body, evidently, they understood Greek. See Introd. ii. § 2.

the wise, and to the unwise Practically, the cultured and the uneducated. He contemplates literaryhearers on one side, and on the other rude tribes, and peasantry and workmen, and women and children. The word rendered "unwise" is a strong one; elsewhere (e.g. Luke 24:25; Galatians 3:1; Titus 3:3;) rendered "fools," "foolish," or the like. Here the Apostle probably uses it as from the point of view of the "wise:" "those whom the philosopher would think to be mind-less."