Here, properly speaking, the letter ends. The Apostle has communicated his mind to the Thessalonians as fully as their situation required; and might end, as he did in the First Epistle, with his benediction. But he remembers the unpleasant incident, mentioned in the beginning of ch. ii., of a letter purporting to be from him, though not really his; and he takes care to prevent such a mistake for the future. This Epistle, like almost all the rest, had been written by some one to the Apostle's dictation; but as a guarantee of genuineness, he closes it with a line or two in his own hand. "The salutation of me Paul with mine own hand, which is the token in every epistle: so I write." What does "so I write" mean? Apparently, "You see the character of my writing; it is a hand quite recognisable as mine; a few lines in this hand will authenticate every letter that comes from me."
Perhaps "every letter" only means every one which he would afterwards write to Thessalonica; certainly attention is not called in all the Epistles to this autographic close. It is found in only two others--1st Corinthians (xvi. 21) and Colossians (iv. 18)--exactly as it stands here, "The salutation of me Paul with mine own hand"; in others it may have been thought unnecessary, either because, like Galatians, they were written throughout in his own hand; or, like 2nd Corinthians and Philemon, were conveyed by persons equally known and trusted by the Apostle and the recipients. The great Epistle to the Romans, to judge from its various conclusions, seems to have been from the very beginning a sort of circular letter; and the personal character, made prominent by the autograph signature, was less in place then. The same remark applies to the Epistle to the Ephesians. As for the pastoral Epistles, to Timothy and Titus, they may have been autographic throughout; in any case, neither Timothy nor Titus was likely to be imposed upon by a letter falsely claiming to be Paul's. They knew their master too well.
If it was possible to make a mistake in the Apostle's lifetime, and to take as his an Epistle which he never wrote, is it impossible to be similarly imposed upon now? Have we reasonable grounds for believing that the thirteen Epistles in the New Testament, which bear his name upon their front, really came from his hand? That is a question which in the last hundred years, and especially in the last fifty, has been examined with the amplest learning and the most minute and searching care. Nothing that could possibly be alleged against the authenticity of any of these Epistles, however destitute of plausibility, has been kept back. The references to them in early Christian writers, their reception in the early Church, the character of their contents, their style, their vocabulary, their temper, their mutual relations, have been the subject of the most thorough investigation. Nothing has ever been more carefully tested than the historical judgment of the Church in receiving them; and though it would be far from true to say that there were no difficulties, or no divergence of opinion, it is the simple truth that the consent of historical critics in the great ecclesiastical tradition becomes more simple and decided. The Church did not act at random in forming the apostolic canon. It exercised a sound mind in embodying in the New Testament of our Lord and Saviour the books which it did embody, and no other. Speaking of Paul in particular, one ought to say that the only writings ascribed to him, in regard to which there is any body of doubtful opinion, are the Epistles to Timothy and Titus. Many seem to feel, in regard to these, that they are on a lower key than the undoubtedly Pauline letters; there is less spirit in them, less of the native originality of the gospel, a nearer approach to moral commonplace; they are not unlike a half-way house between the apostolic and the post-apostolic age. These are very dubious grounds to go upon; they will impress different minds very differently; and when we come to look at the outward evidence for these letters, they are almost better attested, in early Christian writers, than anything else in the New Testament. Their semi-legal character, and the positive rules with which they abound, inferior as they make them in intellectual and spiritual interest to high works of inspiration like Romans and Colossians, seem to have enabled simple Christian people to get hold of them, and to work them out in their congregations and their homes. All that Paul wrote need not have been on one level; and it is almost impossible to understand the authority which these Epistles immediately and universally obtained, if they were not what they claimed to be. Only a very accomplished scholar could appreciate the historical arguments for and against them; yet I do not think it is unfair to say that even here the traditional opinion is in the way, not of being reversed, but of being confirmed.