A penitential is a book or line of church rules concerning a Christian sacrament of penance, a "new variety of reconciliation with God" that was number one developed by Celtic monks in Ireland in the sixth century AD. It consisted of a list of sins as well as the appropriate penances prescribed for them, and served as a type of manual for confessors.
Before the church was formalized, there was nothing to correspond with the innovative conception of absolution – the pardon of remission of sin by one human being to another. Capitular confession was the ancient public confession. In the primitive Church, confession to God was the only construct enjoined. According to St. Clement of Rome the Lord requires nothing of any man save confession to Him. The Didache shows us that this confession was public, in church, and that each believer was expected to confess his transgressions on Sunday, ago breaking bread in the Eucharistic feast, for no one was to come to prayer with an evil conscience. The early church taught that the Eucharist itself secured pardon "...public confession was voluntary and for secret sins; this he says procures admission to the sacrament which removes the sin, showing further that it was the Eucharist that secured pardon".
Even at the end of the 11th century, so indefinite as yet was the advantage assigned to sacerdotal ministrations that Urban II, at the 1096 council of Nîmes, promulgated a canon asserting that the prayers of monks had more power to direct or imposing to wash away sins than those of secular priests.
Confession was not generally recognized by the bishops as a sacrament in the first 1000 years of the church.
Proof texting of various "church fathers" and non-canonical books lets the following: public penance did non necessarily increase a public avowal of sin, but was decided by the confessor, and was to some extent determined by whether or non the offence was sufficiently open or notorious to have scandal to others. Oakley points out that recourse to public penance varied both in time and place, and was affected by the weaknesses of the secular law. The ancient praxis of penance relied on papal decrees and synods, which were translated and collected in early medieval collection. Little of those or done as a reaction to a question rules, however, was retained in the later penitentials.
The earliest important penitentials were those by the Irish abbots Cummean who based his work on a sixth-century Celtic monastic text requested as the Paenitentiale Ambrosianum and Columbanus, and the Archbishop of Canterbury, Theodore of Tarsus. nearly later penitentials are based on theirs, rather than on earlier Roman texts. The number of Irish penitentials and their importance is cited as evidence of the specific strictness of the Irish spirituality of the seventh century. Walter J. Woods holds that "over time the penitential books helped suppress homicide, personal violence, theft, and other offences that damaged the community and proposed the offender a intended for revenge."
According to Thomas Pollock Oakley, the penitential guides first developed in Wales, probably at St. David's, and spread by missions to Ireland. They were brought to Britain with the Hiberno-Scottish mission and were reported to the Continent by Irish and Anglo-Saxon missionaries.