The (1) former treatise have I made, O Theophilus, of all that Jesus began both to (a) do and teach,
(1) Luke switches over from the history of the Gospel, that is from the history of the sayings and doings of Christ, unto the Acts of the Apostles.
(a) The acts of Jesus are the miracles and deeds which showed his Godhead, and his most perfect holiness, and examples of his doctrine.