They could do no wrong; winning so big in so many places that they thought their victory a mandate — their mission itself destiny.

And who could blame them? A popular leader, an emboldened legislature, an unstoppable force.

Until they were stopped.

I'm not talking Democrats in power here, but another party in power there: In Japan, where the ruling party just received a royal drubbing.

After more than a half century of virtually uninterrupted power, the liberal Democrats have been interrupted. Voters not only throwing them out, but virtually throwing all of them out. Liberal Democrats — actually conservatives over there — losing almost 200 seats. The more leftist Democratic Party now controls more than 300 of the 480 lower parliament seats.

That's big, my friends and a big warning and reminder to any party in power anywhere: What voters giveth, they can easily — and often do — take away.

It's happened here, with Republicans who thought their 1994 revolution was etched in stone, until voters etched them out. And it could happen again with Democrats, who took their sweeping victories last year as the stuff of generational change for many years.

If Japan proves anything, it's that what is given often isn't and what is assumed to happen often doesn't.

They say nothing corrupts like power and nothing seduces like it either. Because you read too much into a snapshot and a moment that has passed, and forget the moments that have passed since.

It's why Democrats here focus on election results more than nine months ago and fail to appreciate the anger at town hall meetings nine days ago. Or angry California voters, who shot down government tax increases not even nine weeks ago, risk being blindsided to the arrogance of the past and the arrogance of living in the past.

Nothing humbles election winners like losing. Ask Liberal Democrats in Japan who aren't liberal — or in power — and Democrats in America who increasingly are liberal, and at best, tenuously holding onto power.

Watch Neil Cavuto weekdays at 4 p.m. ET on "Your World with Cavuto" and send your comments to cavuto@foxnews.com