Romans 15:19

in the power of signs and wonders, in the power of the Holy Spirit; so that from Jerusalem, and round about even unto Illyricum,. have fully preached the gospel of Christ;

'in the power of signs and wonders' -Jesus had also used Paul as an instrument to work miracles through. (2 Corinthians 12:12) These miracles were designed to get people's attention, and point them to the message that was being preached by the worker of the miracle. (John 3:2; John 5:36; John 10:37)

'in the power of the Holy Spirit' -'in connection with the Holy Spirit's power' (Lenski p. 884); 'through the power of the Holy Spirit.' (TCNT)

'so that from Jerusalem' -where we find him preaching at the end of Acts chapter 9.

'round about' -'He says that in. grand sweep through Asia Minor and southern Europe he delivered the gospel message and reached as far as Illyricum.' (Lenski p. 885)

'I have fully preached the gospel Christ' -'He had done this by preaching it in every province between the limits named (not to every individual), and had thus discharged his apostolic commission in that part of the Gentile world.' (F.F. Bruce p. 261)

'Illyricum' -'The area in which Paul preached the gospel covered some 1400 miles. Illyricum was. Roman province north of Macedonia which was in recent history part of Yugoslavia.' (Green p. 16)