Rick Perry served 14 years as the governor of Texas. He ran for president twice. But it was 48 seconds on Nov. 9, 2011, that will forever define his brief time as a national figure.

These are those 48 seconds.

Republican presidential candidate Rick Perry had an "oops" moment at the 2011 GOP debate in Detroit when he couldn't remember one of the three government agencies he plans to cut. (NBC)

Perry's inability to remember the third agency he would get rid of if elected president -- a riff that begins at the 22-second mark of the clip above and, mercifully, ends at the 70-second mark -- wasn't the first sign of a crack in the one-time front-runner for the 2012 nod.

Perry's best day in that race was his first day in the race -- the same day as the final Ames (Iowa) Straw Poll. Perry entered the race like a champion, touting his jobs record, his fundraising ability and his conservative bona fides. But after the first few days, it began to be clear that Perry looked better than he sounded. Questions about whether he was up for the race arose with whispers growing daily that his back was a major problem. (He had undergone surgery just before getting into the race.)

Just more than a week before Perry's "oops" moment, he had given what can only be described as a bizarre speech in New Hampshire. The speech was so odd that Perry was forced to deny, on the record, that he has been drunk.

An edited version of Rick Perry's on Oct. 28 speech in Manchester, N.H., has gone viral. Watch the full speech at the Cornerstone Action Dinner. (Nov 2) (Photo: AP) (CBS News)

So, when Perry imploded on the debate stage that November night, it wasn't an exception; it was an affirmation.

But what Perry couldn't have known that night was that his 48-second brain freeze would effectively end not just his chances in 2012, which were already flagging badly, but that it would also invalidate him as a candidate four years later in a very different presidential race. In the 2016 race, Perry was never able to shake the perception that he was just not up to the job; he was mocked for trying to look smart when he donned glasses for this campaign and, everywhere he went, he had to deal with the fact that minds were made up about him -- and not in a good way. He never really had a chance.

What does the fact that Perry's long career will be summed up for most Americans by a stumbling answer that ran less than a minute? That we live in a politics of moments -- moments, good and bad, forever replayed on video and captured in images that burn their way into the public's consciousness?

Take George W. Bush's presidency. Its highest and the lowest moments can effectively be summed up in one picture and one video.

The video, which was the high point of his presidency, came from Bush's visit to Ground Zero shortly after the terrorist attacks of Sept. 11, 2001.

The picture, which came during Bush's flyover tour of the devastation caused by Hurricane Katrina, was the low point.

From "47 percent" to "cling to guns or religion," modern presidential politics has been defined -- or at least heavily shaped -- by moments that the public believe offer some deep(er) insight into who these people seeking to represent them actually are.

Perry was undone by our moments-based political culture. Nothing he said or did after those disastrous 48 seconds in November 2011 mattered. He had been judged and found wanting.

For the 16 Republicans -- and four Democrats -- still seeking the presidency in 2016, Perry should serve as a warning: You can be undone in the modern political environment in the time it takes to tie your shoes.