"The other Evangelists, out of tenderness towards the reputation and honour of Matthew, have abstained from speaking of him as a publican by his ordinary name, and have called him Levi. Both names were his. But Matthew himself, according to what Solomon saith: The just man is the first to accuse himself, (Prov. xviii. 17), and again, in another place: Declare thou thy sins that thou mayest be justified, doth plainly call himself Matthew the publican, to show unto his readers that none need be hopeless of salvation if he will but strive to do better, since he himself had been all of a sudden changed from a publican into an Apostle."
-Reading 7, Matins, Feast of St. Matthew.