But we have this treasure in jars of clay, to show that the surpassing power belongs to God and not to us. ESV

Paul never wanted the ‘jar of clay’ to be confused with the ‘treasure’.

Tom Wright, in his commentary on 2 Corinthians, talks about Sir Oliver Franks, who was the British Ambassador to the United States at the time the cold war began. He describes how he often needed to get urgent, top secret messages between Washington and London. There was a diplomatic bag which went back and forth each day, carrying confidential documents across the Atlantic by air. But when something was ‘really confidential, utterly top secret, and desperately urgent’ he wouldn’t put it in a bag that everyone knew was important. Rather he placed it in an ordinary envelope and sent it by regular mail. Tom Wright adds:

‘What Paul is saying is that there is no chance of anyone confusing the content of the envelope with the very unremarkable envelope itself. The messenger is not important; what matters, vitally and urgently, is the message…The Corinthians had been looking at the envelope – at Paul’s own public figure, his speaking style, and at the fact that he is in and out of trouble, weakness, and now near to death – and they have concluded that there is nothing at all remarkable about him. He ought to look more important than that, surely, if he really is a messenger with a message from the living God! No, says Paul: you’re missing the point. Precisely because of the vital importance of the message, the messenger must be dispensable.’