ACTS An Introduction and Commentary by E.M.Blaiklock

II. THE WRITER OF THE BOOK
Evidence which may be regarded as conclusive supports the view held commonly by the Church since the middle of the second century, that the Acts of the Apostles was written by Luke, the physician-friend and fellow-traveller of Paul.
External evidence is far from negligible. The oldest extant list of New Testament writings, known from the name of its discoverer as the Muratorian Fragment, and dating from the latter half of the second century, lists the third Gospel and the Acts of the Apostles as the work of Luke the physician.
Irenaeus (c. AD 130-c. 200) and Clement of Alexandria (c. AD
150-c. 215) may be quoted in support. Origen (c. AD 185-
c. 254) and Tertullian (c. AD I60-c. 200) bear the same testimony. A living tradition can span a century, and if, therefore, scholars about AD 170 believed that Luke wrote the Acts of the Apostles, their witness cannot be lightly dismissed.
Internal evidence coincides. First, it is clear, and generally admitted, that whoever wrote the third Gospel also wrote the Acts of the Apostles. Analysis of style and language places this matter beyond dispute. Secondly, the evidence of archaeology and epigraphy also points with increasing cogency to an author personally familiar with the world of the first century.
Thirdly, that person was also a physician. His language has been exhaustively examined, and there is no doubt that there is a colouring of expression and a habit of vocabulary consistent only with a close acquaintance with Greek medical terminology. Set beside the fact that the traditional author was, in fact, a physician (Col. iv. 14), this evidence seems conclusive. Fourthly, a plain reading of the text makes it clear that the writer was a companion of Paul in certain of his travels and adventures. In four passages of varying length he writes in the first person (Acts 16verses 10-17: “And after he had seen the vision, immediately we endeavoured to go into Macedonia, assuredly gathering that the Lord had called us for to preach the gospel unto them.
Therefore loosing from Troas, we came with a straight course to Samothracia, and the next day to Neapolis;
And from thence to Philippi, which is the chief city of that part of Macedonia, and a colony: and we were in that city abiding certain days.
And on the sabbath we went out of the city by a river side, where prayer was wont to be made; and we sat down, and spake unto the women which resorted thither.
And a certain woman named Lydia, a seller of purple, of the city of Thyatira, which worshipped God, heard us: whose heart the Lord opened, that she attended unto the things which were spoken of Paul.
And when she was baptized, and her household, she besought us, saying, If ye have judged me to be faithful to the Lord, come into my house, and abide there. And she constrained us.
And it came to pass, as we went to prayer, a certain damsel possessed with a spirit of divination met us, which brought her masters much gain by soothsaying:
The same followed Paul and us, and cried, saying, These men are the servants of the most high God, which shew unto us the way of salvation.

Acts 20:5-15 KJV
These going before tarried for us at Troas.
And we sailed away from Philippi after the days of unleavened bread, and came unto them to Troas in five days; where we abode seven days.
 And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight.
And there were many lights in the upper chamber, where they were gathered together.
And there sat in a window a certain young man named Eutychus, being fallen into a deep sleep: and as Paul was long preaching, he sunk down with sleep, and fell down from the third loft, and was taken up dead.
And Paul went down, and fell on him, and embracing him said, Trouble not yourselves; for his life is in him.
When he therefore was come up again, and had broken bread, and eaten, and talked a long while, even till break of day, so he departed.
And they brought the young man alive, and were not a little comforted.
And we went before to ship, and sailed unto Assos, there intending to take in Paul: for so had he appointed, minding himself to go afoot.
And when he met with us at Assos, we took him in, and came to Mitylene.
And we sailed thence, and came the next day over against Chios; and the next day we arrived at Samos, and tarried at Trogyllium; and the next day we came to Miletus.

Acts 21:1-18
And it came to pass, that after we were gotten from them, and had launched, we came with a straight course unto Coos, and the day following unto Rhodes, and from thence unto Patara:
And finding a ship sailing over unto Phoenicia, we went aboard, and set forth.
Now when we had discovered Cyprus, we left it on the left hand, and sailed into Syria, and landed at Tyre: for there the ship was to unlade her burden. And finding disciples, we tarried there seven days: who said to Paul through the Spirit, that he should not go up to Jerusalem.
And when we had accomplished those days, we departed and went our way; and they all brought us on our way, with wives and children, till we were out of the city: and we kneeled down on the shore, and prayed.
And when we had taken our leave one of another, we took ship; and they returned home again.
And when we had finished our course from Tyre, we came to Ptolemais, and saluted the brethren, and abode with them one day.
And the next day we that were of Paul's company departed, and came unto Caesarea: and we entered into the house of Philip the evangelist, which was one of the seven; and abode with him.
And the same man had four daughters, virgins, which did prophesy.
And as we tarried there many days, there came down from Judaea a certain prophet, named Agabus.
And when he was come unto us, he took Paul's girdle, and bound his own hands and feet, and said, Thus saith the Holy Ghost, So shall the Jews at Jerusalem bind the man that owneth this girdle, and shall deliver him into the hands of the Gentiles.
And when we heard these things, both we, and they of that place, besought him not to go up to Jerusalem.
Then Paul answered, What mean ye to weep and to break mine heart, for I am ready not to be bound only, but also to die at Jerusalem for the name of the Lord Jesus.
And when he would not be persuaded, we ceased, saying, The will of the Lord be done.
And after those days we took up our carriages, and went up to Jerusalem.
There went with us also certain of the disciples of Caesarea, and brought with them one Mnason of Cyprus, an old disciple, with whom we should lodge.
 And when we were come to Jerusalem, the brethren received us gladly.
And the day following Paul went in with us unto James; and all the elders were present.
These passages, on demonstrable linguistic grounds, cannot be dissociated from the rest of the book. In other words, the writer of Acts was the writer of the whole of Acts, including the 'we-sections'. Nor, among the close associates of Paul, is an alternative available. Acts 20 verses 5 and 6 :

“These going before tarried for us at Troas.
And we sailed away from Philippi after the days of unleavened bread, and came unto them to Troas in five days; where we abode seven days,”
appear to exclude Timothy. Timothy was among those waiting for the author at Troas. Neither Titus, a shadowy figure, nor Silas were with Paul on the journey to Rome, or in Rome, and the eyewitness character of these concluding chapters of the book is beyond dispute.
All in all, it would be difficult to find a book in the whole range of ancient literature concerning which a stronger case can be made in support of a traditional authorship. That case has, in fact, been disputed only by those preoccupied on other grounds with establishing a later date than that which is consistent with a Lucan authorship—a species of scholarship happily moribund today.
Of Luke himself little is known. The author who could deliberately turn from the artificial style of his prologue to write his Gospel and its sequel in a strong and effective vernacular was a person not likely to reveal himself too intimately in his work. Tradition has it that he was a native of Antioch, but certain features of the narrative of Philippi make it very likely that he was a native of the Macedonian colony.
If not, he was in all likelihood an Antiochene of Macedonian origin, who worked in Philippi for significant years. Beyond this nothing is known. He must have been a man of singular sweetness of character to earn Paul's adjective 'beloved' (Colossians 4:14). His sympathetic treatment of Paul's adventures, and his unquestioning acceptance of the apostle's leadership, even after the rejection of earnest advice, indicate a person of self-effacing and courageous loyalty. His intellectual capacity is revealed in his work. It is conceived as a unity and the narrative drives straight to its goal. Luke was a man with an unusual capacity for research, and the scholar's ability to strip away irrelevant or dispensable detail. He had an unerring feeling for the significant, an eye for colour and character, and he could tell a story with vividness and clarity. Beyond this he is sought in vain in the pages of his books. In the 'former treatise' he preferred to make his Master The Lord Jesus prominent; in the latter, his distinguished friend the Apostle Paul.