That Theophilus, to whom he sent these two books, was not a simple man, but a governor and prince, is evident from the adjective attached to his name in the Gospel: "most excellent Theophilus" (Lk 1:3). Felix, the governor of Caesarea, and Festus, his successor, are also called most excellent.
Where Theophilus was governor, whence he came, and the other matters concerning him, are unknown.
But when you hear Luke saying, "I made a word concerning all," that is, concerning all the deeds of Jesus Christ, do not think that this contradicts the following words of the Evangelist John: "If they were written one by one, I suppose that even the world itself could not contain the books that would be written" (Jn 21:25).
Luke truly spoke concerning all, but only generally, summarily, and briefly. John says that if Christ's deeds, miracles, and teaching were written one by one, that is, each separately, circumstantially, and in detail, then the whole world could not contain the books written.
Yet John, by the word "I suppose," lessened the force of his statement.
What then does this mean: "until the day on which, after giving commandments to the Apostles through the Holy Spirit"? This means that Luke described in his Gospel not only what Jesus Christ did and commanded the Apostles before His Resurrection. He also described what was commanded by Him after His Resurrection from the dead, until the day on which He ascended from earth to heaven.
First, he related in the Gospel that after His Resurrection Jesus Christ set before the Apostles, through the interpretation of the divine Scriptures, everything Moses and the other Prophets had foretold concerning Him: "And beginning with Moses and all the Prophets, He interpreted to them in all the Scriptures the things concerning Himself" (Lk 24:27).
Second, by the greeting pronounced to them, He gave them the commandment of peace: "And Jesus Himself stood in the midst of them and said to them, 'Peace be to you'" (Lk 24:36).
Third, He commanded them, as eyewitnesses of all His deeds, to preach His name, repentance, and the forgiveness of sins through Him to every nation, beginning from Jerusalem: "Repentance and forgiveness of sins should be preached in His name to all nations, beginning from Jerusalem. You are witnesses of these things" (Lk 24:47-48).
Fourth, He commanded them to remain in Jerusalem until they received the power that was to come upon them from heaven: "Remain in the city of Jerusalem until you are clothed with power from on high" (Lk 24:49).
This is the last commandment that Jesus Christ gave His disciples on the day of His Ascension into heaven. For after saying this, He led them out from Jerusalem as far as Bethany. Having blessed them, "He parted from them and was carried up into heaven" (Lk 24:51).
Everything that the Lord commanded His Apostles, both before His Resurrection and after it, was spiritual and divine. He did and taught everything while being inseparable from the Holy Spirit, since He is one in nature with Him according to the Godhead, and consubstantial with Him.
Therefore Luke says, "through the Holy Spirit."
Thus the whole meaning of these words, set forth most clearly, is this: Theophilus, in my first word, that is, in the Gospel which I wrote and sent to you, I spoke of all the deeds, miracles, and teachings of the Lord Jesus.
I began from the very time when He began to do these things with the Holy Spirit present with Him. I continued until the day on which, after giving His final commandments to the Apostles, as His chosen ones from the whole world, He ascended into heaven (Jn 15:10; Lk 24:51).
What the most blessed Apostle has now stated generally, he next explains in detail, saying thus: v. 3, "To them He also presented Himself alive after His Passion by many infallible proofs, appearing to them during forty days and speaking of the things pertaining to the Kingdom of God." v. 4, "And while eating with them, He commanded them not to depart from Jerusalem, but to wait for the promise of the Father, which you have heard from Me."