Smalcald Article, Part III, Article III on Repentance:

20] Here, too, there was no faith nor Christ, and the virtue of the absolution was not declared to him, but upon his enumeration of sins and his self-abasement depended his consolation. What torture, rascality, and idolatry such confession has produced is more than can be related.

21] As to satisfaction, this is by far the most involved [perplexing] part of all. For no man could know how much to render for a single sin, not to say how much for all. Here they have resorted to the device of imposing a small satisfaction, which could indeed be rendered, as five Paternosters, a day's fast, etc.; for the rest [that was lacking] of the [in their] repentance they were directed to purgatory.

22] Here, too, there was nothing but anguish and [extreme] misery. [For] some thought that they would never get out of purgatory, because, according to the old canons, seven years' repentance is required for a single mortal sin. 23] Nevertheless, confidence was placed upon our work of satisfaction, and if the satisfaction could have been perfect, confidence would have been placed in it entirely, and neither faith nor Christ would have been of use. But this confidence was impossible. For, although any one had done penance in that way for a hundred years, he would still not have known whether he had finished his penance. That meant forever to do penance and never to come to repentance.

24] Here now the Holy See at Rome, coming to the aid of the poor Church, invented indulgences, whereby it forgave and remitted [expiation or] satisfaction, first, for a single instance, for seven years, for a hundred years and distributed them among the cardinals and bishops, so that one could grant indulgence for a hundred years and another for a hundred days. But he reserved to himself alone the power to remit the entire satisfaction.

25] Now, since this began to yield money, and the traffic in bulls became profitable he devised the golden jubilee year [a truly gold-bearing year], and fixed it at Rome. He called this the remission of all punishment and guilt. Then the people came running, because every one would fain have been freed from this grievous, unbearable burden. This meant to find [dig up] and raise the treasures of the earth. Immediately the Pope pressed still further, and multiplied the golden years one upon another. But the more he devoured money, the wider grew his maw.

Later, therefore, he issued them [those golden years of his] by his legates [everywhere] to the countries, until all churches and houses were full of the Golden Year. 26] At last he also made an inroad into purgatory among the dead, first, by founding masses and vigils, afterwards, by indulgences and the Golden Year, and finally souls became so cheap that he released one for a farthing.

27] But all this, too, was of no avail. For although the Pope taught men to depend upon, and trust in, these indulgences [for salvation], yet he rendered the [whole] matter again uncertain. For in his bulls he declares: Whoever would share in the indulgences or a Golden Year must be contrite, and have confessed, and pay money. Now, we have heard above that this contrition and confession are with them uncertain and hypocrisy. Likewise, also no one knew what soul was in purgatory, and if some were therein, no one knew which had properly repented and confessed. Thus he took the precious money [the Pope snatched up the holy pence], and comforted them meanwhile with [led them to confidence in] his power and indulgence, and [then again led them away from that and] directed them again to their uncertain work.

28] If, now [although], there were some who did not believe [acknowledge] themselves guilty of such actual sins in [committed by] thoughts, words, and works,—as I, and such as I, in monasteries and chapters [fraternities or colleges of priests], wished to be monks and priests, and by fasting, watching, praying, saying Mass, coarse garments, and hard beds, etc., fought against [strove to resist] evil thoughts, and in full earnest and with force wanted to be holy, and yet the hereditary, inborn evil sometimes did in sleep what it is wont to do (as also St. Augustine and Jerome among others confess),—still each one held the other in esteem, so that some, according to our teaching, were regarded as holy, without sin and full of good works, so much so that with this mind we would communicate and sell our good works to others, as being superfluous to us for heaven. This is indeed true, and seals, letters, and instances [that this happened] are at hand.