The annual long-term budget outlook from the Congressional Budget Office is an incredible document and, at least ostensibly, a moment to reflect on U.S. government spending and taxing. Instead, every year, it acts more like a magic mirror, somehow perfectly reflecting the previous biases of each reader.

Consider the CBO's opening chart this year, which appears at the top of this article. Stare deeply into its green and darker green hues. Squint and meticulously trace the federal spending and revenues lines. What do you see?

Fiscal conservative Jim Pethokoukis sees the case for fiscal conservatism. Don't-worry-about-the-debt economist Brad DeLong finds cause to not worry about the debt. I think Brad is right for now and Jim less right, but who cares what I think? After writing about this stuff for a few years, it occurs to me that I will never change readers' mind about the debt. Ever. If you locked a hundred budget wonks in a room with one simple debt graph and told them they couldn't leave until they agreed on what it meant, cannibalism would come before consensus.

But you know who has changed its mind? The CBO. Director Doug Elmendorf admitted as much in a presentation last week.

In 2007, the CBO thought our debt burden was going to fall to hysterically low levels (see: YELLOW line). Then the Great Recession happened, and the CBO revised its projections (see: GREY). But even a year ago, it was still wrong by billions of dollars of annual deficits ...