Everybody has at some point lost their train of thought. I’ve set out to make multiple points on television and forgotten one, or forgotten if I had run through them all, before myself. So on one level, Rick Perry’s inability to remember the third federal agency he would eliminate is simply part of being human.

Unfortunately, it also seems to be a big part of what it means to be candidate Rick Perry. There are small debate gaffes that seem to sum up what’s wrong with an entire campaign — Bob Dole’s “Democrat wars” line in 1976, George Bush looking at his watch in 1992, Al Gore sighing prissily and behaving like a lunatic in 2000. This is one of them.

Perry has bombed every debate since he entered the race. He has generally seemed uniformed and uninterested in matters of substance. His forgetfulness was the only memorable thing about his entire performance. Fairly or not, it has raised questions about his intellect. Perry has also raised questions about his two biggest assets: his conservatism relative to Mitt Romney and his electablity relative to all the non-Romney candidates. Perry’s slip symbolizes both problems. It is hard to imagine him successfully debating President Obama. And what conservative can’t come up with considerably more than three agencies he would like to abolish?

The Perry camp no doubt is aware that this was a significant problem. A Washington Post blogger tweeted that a major Perry fundraiser told him, “Perry campaign is over. Time for him to go home and refocus on being Gov of TX.” Perry took to the spin room himself to admit he’d stepped in it after the debate. Not a good showing, and not for the first time. We’ll see if it’s the last.