Ancient Epitome of Canon XII.
Those who endured violence and were seen to have resisted, but who afterwards yielded to wickedness, and returned to the army, shall be excommunicated for ten years. But in every case the way in which they do their penance must be scrutinized. And if anyone who is doing penance shews himself zealous in its performance, the bishop shall treat him more leniently than had he been cold and indifferent.
The abuse of this power, namely, of granting under certain circumstances a relaxation in the penitential exercises enjoined by the canons -- led, in later times, to the practice of commuting such exercises for money payments, etc.
In his last contests with Constantine, Licinius had made himself the representative of heathenism; so that the final issue of the war would not be the mere triumph of one of the two competitors, but the triumph or fall of Christianity or heathenism. Accordingly, a Christian who had in this war supported the cause of Licinius and of heathenism might be considered as a lapsus, even if he did not formally fall away. With much more reason might those Christians be treated as lapsi who, having conscientiously given up military service (this is meant by the soldier's belt), afterwards retracted their resolution, and went so far as to give money and presents for the sake of readmission, on account of the numerous advantages which military service then afforded. It must not be forgotten that Licinius, as Zonaras and Eusebius relate, required from his soldiers a formal apostasy; compelled them, for example, to take part in the heathen sacrifices which were held in the camps, and dismissed from his service those who would not apostatize.
This canon (which in the Prisca and the Isidorian version stands as part of canon 11) deals, like it, with cases which had arisen under the Eastern reign of Licinius, who having resolved to "purge his army of all ardent Christians" (Mason, Persec. of Diocl. p.308), ordered his Christian officers to sacrifice to the gods on pain of being cashiered (compare Euseb. H. E. x.8; Vit. Con. i.54). It is to be observed here that military life as such was not deemed unchristian. The case of Cornelius was borne in mind. "We serve in your armies," says Tertullian, Apol.42 (although later, as a Montanist, he took a rigorist and fanatical view, De Cor.11), and compare the fact which underlies the tale of the "Thundering Legion," -- the presence of Christians in the army of Marcus Aurelius. It was the heathenish adjuncts to their calling which often brought Christian soldiers to a stand (see Routh. Scr. Opusc. i.410), as when Marinus' succession to a centurionship was challenged on the ground that he could not sacrifice to the gods (Euseb. H. E. vii.15). Sometimes, indeed, individual Christians thought like Maximilian in the Martyrology, who absolutely refused to enlist, and on being told by the proconsul that there were Christian soldiers in the imperial service, answered, "Ipsi sciunt quod ipsis expediat" (Ruinart, Act. Sanc. p.341). But, says Bingham (Antiq. xi.5, 10), "the ancient canons did not condemn the military life as a vocation simply unlawful....I believe there is no instance of any man being refused baptism merely because he was a soldier, unless some unlawful circumstance, such as idolatry, or the like, made the vocation sinful." After the victory of Constantine in the West, the Council of Arles excommunicated those who in time of peace "threw away their arms" (can.2). In the case before us, some Christian officers had at first stood firm under the trial imposed on them by Licinius. They had been "called by grace" to an act of self-sacrifice (the phrase is one which St. Augustine might have used); and had shown "their eagerness at the outset" ("primum suum ardorem," Dionysius; Philo and Evarestus more laxly, "primordia bona;" compare ten agapen sou ten proten, Rev. ii.4). Observe here how beautifully the ideas of grace and free will are harmonized. These men had responded to a Divine impulse: it might seem that they had committed themselves to a noble course: they had cast aside the "belts" which were their badge of office (compare the cases of Valentinian and Valens, Soc. iii.13, and of Benevolus throwing down his belt at the feet of Justina, Soz. vii.13). They had done, in fact, just what Auxentius, one of Licinius' notaries, had done when, according to the graphic anecdote of Philostorgius (Fragm.5), his master bade him place a bunch of grapes before a statue of Bacchus in the palace-court; but their zeal, unlike his, proved to be too impulsive -- they reconsidered their position, and illustrated the maxim that in morals second thoughts are not best (Butler, Serm.7), by making unworthy attempts -- in some cases by bribery -- to recover what they had worthily resigned. (Observe the Grecised Latinism benephikiois and compare the Latinisms of St. Mark, and others in Euseb. iii.20, vi.40, x.5.) This the Council describes in proverbial language, probably borrowed from 2 Pet. ii.22, but, it is needless to say, without intending to censure enlistment as such. They now desired to be received to penance: accordingly they were ordered to spend three years as Hearers, during which time "their purpose, and the nature (eidos) of their repentance" were to be carefully "examined." Again we see the earnest resolution of the Council to make discipline a moral reality, and to prevent it from being turned into a formal routine; to secure, as Rufinus' abridgment expresses it, a repentance "fructuosam et attentam." If the penitents were found to have "manifested their conversion by deeds, and not in outward show (schemati), by awe, and tears, and patience, and good works" (such, for instance, Zonaras comments, as almsgiving according to ability), "it would be then reasonable to admit them to a participation in the prayers," to the position of Consistentes, "with permission also to the bishop to come to a yet more indulgent resolution concerning them," by admitting them to full communion. This discretionary power of the bishop to dispense with part of a penance-time is recognized in the fifth canon of Ancyra and the sixteenth of Chalcedon, and mentioned by Basil, Epist.217, c.74. It was the basis of "indulgences" in their original form (Bingham, xviii.4, 9). But it was too possible that some at least of these lapsi might take the whole affair lightly, "with indifference" adiaphoros -- not seriously enough, as Hervetas renders -- just as if, in common parlance, it did not signify: the fourth Ancyrene canon speaks of lapsi who partook of the idol-feast adiaphoros as if it involved them in no sin (see below on Eph.5, Chalc.4). It was possible that they might "deem" the outward form of "entering the church" to stand in the narthex among the Hearers (here, as in c.8, 19, schema denotes an external visible fact) sufficient to entitle them to the character of converted penitents, while their conduct out of church was utterly lacking in seriousness and self-humiliation. In that case there could be no question of shortening their penance time, for they were not in a state to benefit by indulgence: it would be, as the Roman Presbyters wrote to Cyprian, and as he himself wrote to his own church, a "mere covering over of the wound" (Epist.30, 3), an "injury" rather than "a kindness" (De Lapsis, 16); they must therefore "by all means" go through ten years as Kneelers, before they can become Consistentes.
There is great difficulty about the last phrase and Gelasius of Cyzicus, the Prisca, Dionysius Exiguus, the pseudo-Isidore, Zonaras and most others have considered the "not" an interpolation. I do not see how dropping the "not" makes the meaning materially clearer.