The Second Epistle to the Corinthians is a book in the New Testament, written by Paul the Apostle. In this book, sometimes called Paul's Stormy Weather Epistle, Paul is at his most personal in dealing with the brethren at Corinth. Paul encourages the Christians to examine themselves (2 Cor. 13:5) to test whether they are to be found in Christ as a father helps his children to mature to become the image of Christ himself.
(Summary from Wikipedia adapted by Sam Stinson)