The purpose of this paper is to investigate and compare the methods of expressing purpose in four letters written by the Apostle Paul and in the Epistle to the Hebrews. The four epistles of St. Paul which have been studied are the one to the Romans, both letters to the Corinthians, and the one to the Galatians. It is hoped that some light might be shed on the probability or improbability of the Pauline authorship of the Epistle to the Hebrews