Today’s announcement that Tom DeLay will be giving up his reelection campaign and his seat in Congress, amidst the unending swirl of scandals surrounding him, reminds me of an old editorial cartoon that used to be used as a training aid for investigative reporters.

The cartoon was drawn in the late 1800s by Thomas Nast and entitled “The Many Pockets of a Politician’s Coat.” It showed money being stuffed into every conceivable pocket of a portly politician, by a variety of supplicants seeking favors and bearing cash. The cartoon was a favorite of Kent Cooper, who for many years ran the Federal Election Commission’s public records office and was a regular at training seminars for journalists. He used the illustration to impress upon reporters how important it was to look not just for direct campaign contributions, but for all those indirect pockets that accomplish the same goal by less visible means.

Maybe it’s a job for the spouse, maybe a golfing trip to Scotland. Or maybe, as in the case of Tom DeLay, it’s a scheme for shifting funds to state candidates through federal party committees, or browbeating the lobbying community on K Street to hire more Republicans against the threat of losing their access.

In the case of Mr. DeLay, there may still be pockets no one has looked into yet – but enough of them have been exposed that it has finally brought down the man who once was arguably the most powerful politician on Capitol Hill.

Most certainly, when you’re trying to assess the friends and relationships of an important politician, you want to start by taking a deep look at the direct contributions to their campaigns. But the message of the Thomas Nast cartoon – and of the long descent of Tom DeLay – is to keep looking for those other, less public, pockets. And to dig like mad if there’s anything inside.