3 it seemed fitting for me as well, having investigated everything carefully from the beginning, to write it out for you in consecutive order, most excellent Theophilus;Luke 1:3–4 (NAS)
4 so that you may know the exact truth about the things you have been taught.
Luke tells us that from the beginning many undertook the task of documenting the story of Jesus in order to pass it down and on. Those interviewed were eyewitnesses to and custodians of the gospel. There was a common understanding that something world-changing had happened that everyone should know. Luke was a medical doctor and therefore a scientist. What appeared lacking was a comprehensive investigation from beginning, and in this case, to the beginning. Now I would say Matthew did this quite well himself, but more for the benefit of the Jews. The good doctor was aiming to relay the “exact truth” to the masses, Gentiles more specifically, and chose the honorable and trusted official Theophilus to get the word out.