Paul, formerly called Saul, an apostle outside the number of the twelve apostles, was of the tribe of Benjamin and the town of Giscalis in Judea. When this was taken by the Romans he removed with his parents to Tarsus in Cilicia. Sent by them to Jerusalem to study law he was educated by Gamaliel, a most learned man whom Luke mentions. But after he had been present at the death of the martyr Stephen and had received letters from the high priest of the temple for the persecution of those who believed in Christ, he proceeded to Damascus, where constrained to faith by a revelation, as it is written in the Acts of the apostles, he was transformed from a persecutor into an elect vessel.
As Sergius Paulus Proconsul of Cyprus was the first to believe in his preaching, he took his name from him because he had subdued him to faith in Christ, and having been joined by Barnabas, after traversing many cities, he returned to Jerusalem and was ordained apostle to the Gentiles by Peter, James and John. And because a full account of his life is given in the Acts of the Apostles, I only say this, that the twenty-fifth year after our Lord's passion, that is the second of Nero, at the time when Festus Procurator of Judea succeeded Felix, he was sent bound to Rome, and remaining for two years in free custody, disputed daily with the Jews concerning the advent of Christ.
It ought to be said that at the first defence, the power of Nero having not yet been confirmed, nor his wickedness broken forth to such a degree as the histories relate concerning him, Paul was dismissed by Nero, that the gospel of Christ might be preached also in the West. As he himself writes in the second epistle to Timothy, at the time when he was about to be put to death dictating his epistle as he did while in chains; “At my first defence no one took my part, but all forsook me: may it not be laid to their account.
But the Lord stood by me and strengthened me; that through me the message might be fully proclaimed and that all the Gentiles might hear, and I was delivered out of the mouth of the lion” — clearly indicating Nero as lion on account of his cruelty. And directly following he says “The Lord delivered me from the mouth of the lion” and again shortly “The Lord delivered me from every evil work and saved me unto his heavenly kingdom,” for indeed he felt within himself that his martyrdom was near at hand, for in the same epistle he announced “for I am already being offered and the time of my departure is at hand.” He then, in the fourteenth year of Nero on the same day with Peter, was beheaded at Rome for Christ's sake and was buried in the Ostian way, the twenty-seventh year after our Lord's passion.
He wrote nine epistles to seven churches: To the Romans one, To the Corinthians two, To the Galatians one, To the Ephesians one, To the Philippians one, To the Colossians one, To the Thessalonians two; and besides these to his disciples, To Timothy two, To Titus one, To Philemon one. The epistle which is called the Epistle to the Hebrews is not considered his, on account of its difference from the others in style and language, but it is reckoned, either according to Tertullian to be the work of Barnabas, or according to others, to be by Luke the Evangelist or Clement afterwards bishop of the church at Rome, who, they say, arranged and adorned the ideas of Paul in his own language, though to be sure, since Paul was writing to Hebrews and was in disrepute among them he may have omitted his name from the salutation on this account.
He being a Hebrew wrote Hebrew, that is his own tongue and most fluently while the things which were eloquently written in Hebrew were more eloquently turned into Greek and this is the reason why it seems to differ from other epistles of Paul. Some read one also to the Laodiceans but it is rejected by everyone.
Source: De Viris Illustribus (Illustrious Men) (New Advent)