If you have ever been in any of the drill halls of the famous regiments of the army, you will have seen that in some of them the walls are covered with great murals, paintings of battle scenes, historical battles. They are very graphic, very gory also.
What was the discipline? Well, this was the incestuous man of 1 Corinthians. There is another view, started probably shortly before AD200 when Tertullian formed the view that there was an intervening epistles and the apostle Paul is not here referring to the incestuous man of 1 Corinthians but perhaps something else had happened. Paul perhaps had been severely insulted or resisted by some of the people and an apology was called for. All this kind of thing is imagined and put in. Now that theory died a death, one would have thought, many, many centuries ago, but in more modern times, at least in the last century, it came back really through the writings of unbelieving, cynical liberal scholars. There is a missing epistle in between 1 and 2 Corinthians, they said, and some to go so far as to say, oh we know where it is, it is the last four chapters of 2 Corinthians. They are different in character. But the traditional view and the sensible view is that there is no imagined missing epistle, but what the apostle Paul is talking about here in 2 Corinthians is the need now to restore the notorious sinner who was dealt with in 1 Corinthians.