Confession, specifically the practice of confessing one's sins to a priest, is a quite common practice in the Catholic Church. When and how did this sacrament first originate and become codified as standard Catholic practice?
The "ear confession" as we know it today is an invention of Irish monks (some 6th century? I'm not sure). Before that time, only heavy sins (especially renouncing Christ) were confessed in front of whole congregation. Private confession allowed to confess all sins. This practice spread with Irish missionaries quickly. It was codified as mandatory (at least once a year) on IVth Lateran council (1215).
EDIT: wikipedia on the Sacrament of Penance (Catholic Church) focuses on penance, so the beginning of the practice of confession is bit obscured, but it gives further details and approves the codification in 1215.
EDIT 2: wikipedia article on Celtic Christianity gives more details and cites Medieval Handbooks of Penance.
This account seems implausible given that the Eastern Orthodox practice of confession is essentially the same as the Roman Catholic. Nov 28, 2012 at 23:17
What exactly is implausible? If it's the origin of individual confession in Ireland, I'll try to find some other sources, preferebly some explaining how it spread throughout Europe. I've read at least two books on this topic, one of them written by an Orthodox priest (unfortunately, the books were in Czech, so I can't just link them).– PavelNov 29, 2012 at 10:08
@BenDunlap By all accounts I've heard, this is one of the few practices which the East learned from the West. Those have happened you know. Nov 29, 2012 at 18:41
1@Alypius Good point. (Clearly the rest of us didn't take the time to actually check the resource.) You should submit an answer!– svidgenMar 26, 2013 at 20:58
1I would suggest pointing out that confession as such was always secret—at least, it was supposed to be. (We have records of popes and other bishops condemning the practice of public confession.) What was different in the first few centuries is that the penances (at least for very grave offenses) were public. (Of course, in the case of certain kinds of offenses—e.g., adultery—it was often easy to tell what offenses penitents committed—which is one reason that fully private confession became more popular). Apr 5, 2016 at 13:00