Romans 15:19
Through mighty signs and wonders - By stupendous and striking miracles; see the note at Acts 2:43. Paul here refers, doubtless, to the miracles which he had himself performed; see Acts 19:11-12, "And God wrought special miracles by the hands of Paul," etc.
By the power of the Spirit of God - This may either be connected with signs and wonders, and then it will mean that those miracles were performed by the power of the Holy Spirit; or it may constitute a new subject, and refer to the gift of prophecy, the power of speaking other languages. Which is its true meaning cannot, perhaps, be ascertained. The interpretations "agree" in this, that he traced his success in "all" things to the aid of the Holy Spirit.
So that from Jerusalem - Jerusalem, as a "center" of his work; the center of all religious operations and preaching under the gospel. This was not the place where "Paul" began to preach Galatians 1:17-18, but it was the place where the "gospel" was first preached, and the apostles began to reckon their success from that as a point; compare the note at Luke 24:49.
And round about - ́ ́ͅ kai kuklō . In a circle. That is, taking Jerusalem as a center, he had fully preached round that center until you come to Illyricum.
Unto Illyricum - Illyricum was a province lying to the northwest of Macedonia, bounded north by a part of Italy and Germany, east by Macedonia, south by the Adriatic, west by Istria. It comprehended the modern Croatia and Dalmatia. So that taking Jerusalem as a center, Paul preached not only in Damascus and Arabia, but in Syria, in Asia Minor, in all Greece, in the Grecian Islands, and in Thessaly and Macedonia. This comprehended no small part of the then known world; "all" of which had heard the gospel by the labors of one indefatigable man There is no where in the Acts express mention of Paul' s going "into" Illyricum; nor does the expression imply that he preached the gospel "within" it, but only "unto" its borders. It may have been, however, that when in Macedonia, he crossed over into that country; and this is rendered somewhat probable from the fact that "Titus" is mentioned as having gone into "Dalmatia" II Timothy 4:10, which was a part of Illyricum.
I have fully preached - The word used here means properly "to fill up" ́ peplērōkenai , "to complete," and here is used in the sense of "diffusing abroad," or of "filling up" all that region with the gospel; compare II Timothy 4:17. It means that he had faithfully diffused the knowledge of the gospel in all that immense country.