When I was a young reporter, in a climate full of great political change and anger and revenge and sniping from the shadows that was very much like the Washington of today, I learned a valuable lesson about sources.

It involved a mayor who threatened the established order of Chicago, a secretly recorded tape released to damage that mayor’s reputation and unnamed sources.

The art of the leak is the way politics works everywhere, and I’m reminded of it now, as CNN burns its credibility in its war with President Donald Trump with a botched anti-Trump story that has forced the resignation of three senior CNN journalists.

Because in this modern war, waged by CNN and much of what we call the Beltway journalism…