Luke introduced his Gospel in a classical literary fashion. [source][source][source]
"It was customary among the great Greek and Hellenistic historians, including the first-century Jewish writer Josephus, to explain and justify their work in a preface. Their object was to assure the reader of their capability, thorough research, and reliability." [1][source]
Luke"s introduction contrasts with Matthew"s genealogy, Mark"s title statement, and John"s theological prologue. It would have been what a cultured Greek would have expected to find at the beginning of a reputable historical work. It is all one sentence in Greek. [source][source][source]