(My mirror of a large version of this graphic)
If you're up for walking through an intelligent mathematical proof of this concept, Brad DeLong was nice enought to prepare one just for you:
I Really Cannot Understand Why Anyone Would Do This.

Now--one year later--things are very different indeed! The numbers in the back of the 2004 Budget documents project that the budget year that began when Clinton was still President will be America's last surplus year, ever. The policies proposed in the 2004 Budget are projected to see the deficit widen steadily to 17.5 percent of GDP by 2050. By that date debt held by the public is projected to be 229.4 percent of GDP--a debt and deficit level that no economy could possibly sustain.