The reader has now had an opportunity of judging for himself whether the internal evidence favours any other view of the authorship of The Shepherd, than that which I have adopted. Its apparent design is to meet the rising pestilence of Montanism, and the perils of a secondary stage of Christianity. This it attempts to do by an imaginary voice from the first period. Avoiding controversy, Hermas presents, in the name of his earlier synonyme, a portraiture of the morals and practical godliness which were recognised as "the way of holiness" in the apostolic days. In so doing, he falls into anachronisms, of course, as poets and romancers must. These are sufficiently numerous to reveal the nature of his production, and to prove that the author was not the Hermas of the story.
The authorship was a puzzle and a problem during the earlier discussions of the learned. An anonymous poem (falsely ascribed to Tertullian, but very ancient) did, indeed, give a clue to the solution:--
"--deinde Pius, Hermas cui germine frater,
Angelicus Pastor, quia tradita verba locutus."
To say that there was no evidence to sustain this, is to grant that it doubles the evidence when sufficient support for it is discovered. This was supplied by the fragment found in Milan, by the erudite and indefatigable Muratori, about a hundred and fifty years ago. Its history, with very valuable notes on the fragment itself, which is given entire, may be found in Routh's Reliquiæ.  Or the English reader may consult Westcott's very luminous statement of the case.  I am sorry that Dr. Donaldson doubts and objects; but he would not deny that experts, at least his equals,  accept the Muratorian Canon, which carries with it the historic testimony needed in the case of Hermas. All difficulties disappear in the light of this evidence. Hermas was brother of Pius, ninth Bishop of Rome (after Hyginus, circ. a.d. 157), and wrote his prose idyl under the fiction of his Pauline predecessor's name and age. This accounts (1) for the existence of the work, (2) for its form of allegory and prophesying, (3) for its anachronisms, (4) for its great currency, and (5) for its circulation among the Easterns, which was greater than it enjoyed in the West; and also (6) for their innocent mistake in ascribing it to the elder Hermas.
1. The Phrygian enthusiasm, like the convulsionism of Paris  in the last century, was a phenomenon not to be trifled with; especially when it began to threaten the West. This work was produced to meet so great an emergency.
2. "Fire fights fire," and prophesyings are best met by prophesyings. These were rare among the Orthodox, but Hermas undertook to restore those of the apostolic age; and I think this is what is meant by the tradita verba of the old poem, i.e., words "transmitted or bequeathed traditionally" from the times of Clement. Irenæus, the contemporary of this Hermas, had received the traditions of the same age from Polycarp: hence the greater probability of my conjecture that the brother of Pius compiled many traditional prophesyings of the first age.
3. Supposing the work to be in fact what it is represented to be in fiction, we have seen that it abounds with anachronisms. As now explained, we can account for them: the second Hermas forgets himself, like other poets, and mixes up his own period with that which he endeavours to portray.
4 and 5. Written in Greek, its circulation in the West was necessarily limited; but, as the plague of Montanism was raging in the East, its Greek was a godsend, and enabled the Easterns to introduce it everywhere as a useful book. Origen values it as such; and, taking it without thought to be the work of the Pauline Hermas, attributes to it, as a fancy of his own,  that kind of inspiration which pertained to early "prophesyings." This conjecture once started, "it satisfied curiosity," says Westcott, "and supplied the place of more certain information; but, though it found acceptance, it acquired no new strength." 
6. Eusebius and Jerome  merely repeat the report as an on dit, and on this slender authority it travelled down. The Pauline Hermas was credited with it; and the critics, in their researches, find multiplied traces of the one mistake, as did the traveller whose circuits became a beaten road under the hoofs of his own horse.
If the reader will now turn back to the Introductory Note of the Edinburgh editors, he will find that the three views of which they take any serious notice are harmonized by that we have reached. (1) The work is unquestionably, on its face, the work of the Pauline Hermas. (2) But this is attributable to the fact that it is a fiction, or prose poem. (3) And hence it must be credited to the later Hermas, whose name and authorship are alone supported by external testimony, as well as internal evidence.
(Similitude Ninth, cap. xi. p. 47, note 1.)
Westcott is undoubtedly correct in connecting this strange passage with one of the least defensible experiments of early Christian living. Gibbon finds in this experiment nothing but an opportunity for his scurrility.  A true philosopher will regard it very differently; and here, once and for all, we may speak of it somewhat at length. The young believer, a member, perhaps, of a heathen family, daily mixed up with abominable manners, forced to meet everywhere, by day, the lascivious hetæræ of the Greeks or those who are painted by Martial among the Latins, had no refuge but in flying to the desert, or practising the most heroic self-restraint if he remained with the relations and companions of his youth. If he went to the bath, it was to see naked women wallowing with vile men: if he slept upon the housetop, it was to throw down his mat or rug in a promiscuous stye of men and women.  This alike with rich and poor; but the latter were those among whom the Gospel found its more numerous recruits, and it was just these who were least able to protect themselves from pollutions. Their only resource was in that self-mastery, out of which sprung the Encraty of Tatian and the Montanism of Tertullian. Angelic purity was supposed to be attainable in this life; and the experiment was doubtless attended with some success, among the more resolute in fastings and prayer. Inevitably, however, what was "begun in the spirit," ended "in the flesh," in many instances. To live as brothers and sisters in the family of Christ, was a daring experiment; especially in such a social atmosphere, and amid the domestic habits of the heathen. Scandals ensued. Canonical censures were made stringent by the Church; and, while the vices of men and the peril of persecution multiplied the anchorites of the desert, this mischief was crushed out, and made impossible for Christians. "The sun-clad power of chastity," which Hermas means to depict, was no doubt gloriously exemplified among holy men and women, in those heroic ages. The power of the Holy Ghost demonstrated, in many instances, how true it is, that, "to the pure, all things are pure." But the Gospel proscribes everything like presumption and "leading into temptation." The Church, in dealing with social evils, often encouraged a recourse to monasticism, in its pure form; but this also tended to corruption. To charge Christianity, however, with rash experiments of living which it never tolerated, is neither just nor philosophical. We have in it an example of the struggles of individuals out of heathenism,--by no means an institution of Christianity itself. It was a struggle, which, in its spirit, demands sympathy and respect. The Gospel has taught us to nauseate what even a regenerated heathen conceived to be praiseworthy, until the Christian family had become a developed product of the Church. 
The Gospel arms its enemies against itself, by elevating them infinitely above what they would have been without its influences. Refined by its social atmosphere, but refusing its sanctifying power, they gloat over the failures and falls of those with whom their own emancipation was begun. Let us rather admire those whom she lifted out of an abyss of moral degradation, but whose struggles to reach the high levels of her precepts were not always successful. Yet these very struggles were heroic; for all their original habits, and all their surroundings, were of the sort "which hardens all within, and petrifies the feeling."
The American editor has devoted more than his usual amount of annotation to Hermas, and he affectionately asks the student not to overlook the notes, in which he has condensed rather than amplified exposition. It has been a labour of love to contribute something to a just conception of The Shepherd, because the Primitive Age has often been reproached with its good repute in the early churches. So little does one generation comprehend another! When Christians conscientiously rejected the books of the heathen, and had as yet none of their own, save the Sacred Scriptures, or such scanty portions of the New Testament as were the treasures of the churches, is it wonderful that the first effort at Christian allegory was welcomed, especially in a time of need and perilous temptation?