The sources of information employed by St. Luke can sometimes be determined with a high degree of probability. Where he did not draw upon his own recollections he could often rely upon those of St. Paul. The apostle was, as we should expect, in the habit of narrating his own experiences (cf. 2 Cor. i. 8-10; xii. 9; Gal. i. 11-ii. 14; Phil. iii. 3-7; Rom. xv. 16-32). Acts xxi. 19; xiv. 27; xv. 3, 12, 26, show how St. Paul related his travels. Acts i.-v. probably incorporates an early Jewish Christian document, and contains features which unmistakably point to the truthfulness of the record. A good deal of information was probably obtained from John Mark: it was to the house of Mark's mother that St. Peter made his way after his escape from prison recorded in ch. xii. As St. Mark was with St. Luke and St. Paul at Rome, and acted as St. Peter's interpreter, St. Luke had the opportunity of learning from him many facts concerning St. Peter. St. Barnabas also perhaps furnished some details concerning the history of the early Church at Jerusalem. Some of the converts who fled from Judaea to Antioch (xi. 19) were probably men who witnessed the wonders of the Day of Pentecost. And if St. Luke was a Christian of Antioch, as tradition says, he may have made inquiries of these converts. {108} From Philip the evangelist, St. Luke may have learnt the history of events with which Philip was concerned, as he stayed with him at Caesarea (xxi. 8-12), and he also knew Mnason, who was one of the "original" disciples of Pentecost (xxi. 16). Finally, we notice that St. Luke had intercourse with St. James, the Bishop of Jerusalem, himself (xxi. 18). [Sidenote: Date.] We have seen above (p. 68) that St. Luke's Gospel was probably written soon after A.D. 70. As Acts i. 1 shows that Acts was written later than the Gospel, and as there is just enough difference in style between the two books to encourage the idea that Acts was not written immediately after the Gospel, we may reasonably place Acts between A.D. 75 and 80.